NCP3170 Datasheet by ON Semiconductor

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© Semiconductor Components Industries, LLC, 2014
March, 2017 − Rev. 6 1Publication Order Number:
NCP3170/D
NCP3170
Synchronous PWM
Switching Converter
The NCP3170 is a flexible synchronous PWM Switching Buck
Regulator. The NCP3170 operates from 4.5 V to 18 V, sourcing up to
3 A and is capable of producing output voltages as low as 0.8 V.
The NCP3170 also incorporates current mode control. To reduce the
number of external components, a number of features are internally set
including soft start, power good detection, and switching frequency.
The NCP3170 is currently available in an SOIC−8 package.
Features
4.5 V to 18 V Operating Input Voltage Range
90 mW High-Side, 25 mW Low-Side Switch
FMEA Fault Tolerant During Pin Short Test
3 A Continuous Output Current
Fixed 500 kHz and 1 MHz PWM Operation
Cycle-by-Cycle Current Monitoring
1.5% Initial Output Accuracy
Internal 4.6 ms Soft-Start
Short-Circuit Protection
Turn on Into Pre-bias
Power Good Indication
Light Load Efficiency
Thermal Shutdown
These are Pb-Free Devices
Typical Applications
Set Top Boxes
DVD/Blu−rayt Drives and HDD
LCD Monitors and TVs
Cable Modems
PCIe Graphics Cards
Telecom/Networking/Datacom Equipment
Point of Load DC/DC Converters
Figure 1. Typical Application Circuit
NCP3170
FB1
V
IN
3.3 V
EN
VIN
VSW
AGND
COMP
PG
PGND
RC
R1
R2
L1 4.7 mH
C1
22 mF
C2, C3
22 mF
CC
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SOIC−8 NB
CASE 751
MARKING DIAGRAM
3170x
ALYW
G
1
8
PIN CONNECTIONS
COMPFB
ENAGND
PGVIN
VSW
PGND
(Top View)
Device Package Shipping
ORDERING INFORMATION
NCP3170ADR2G SOIC−8
(Pb−Free) 2,500/Tape & Ree
l
For information on tape and reel specifications,
including part orientation and tape sizes, please
refer to our Tape and Reel Packaging Specification
s
Brochure, BRD8011/D.
NCP3170BDR2G SOIC−8
(Pb−Free) 2,500/Tape & Ree
l
3170x = Specific Device Code
x = A or B
A = Assembly Location
L = Wafer Lot
Y = Year
W = Work Week
G= Pb-Free Package
Figure 2. NCP3170 Block Diagram www.0nsemi.com 2
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Figure 2. NCP3170 Block Diagram
hs
EN UVLO
POR
Power
Control
(PC)
VDD
Driver
Voltage
Clamp
VCV
VCL
VIN
0.030 V/A
Current
Sense
Reference
ORing
Circuit
Soft Start
FB
COMP
PG
+
+
SSlope
Compensation
Oscillator SSETQ
RCLRQ
Soft Start
Complete
998 mV
867 mV
728 mV
+
+
+
AGND
Over
Temperature
Protection
Zero
Current
Detection
VSW
PGND
NDRV
PDRV
VIN
VCW
VCL
Logic HS
LS
Pulse by
Pulse
Current
Limit
VSW
Table 1. PIN FUNCTION DESCRIPTION
Pin Pin Name Description
1 PGND The power ground pin is the high current path for the device. The pin should be soldered to a large copper
area to reduce thermal resistance. PGND needs to be electrically connected to AGND.
2 VIN The input voltage pin powers the internal control circuitry and is monitored by multiple voltage comparators.
The VIN pin is also connected to the internal power PMOS switch and linear regulator output. The VIN pin
has high di/dt edges and must be decoupled to ground close to the pin of the device.
3 AGND The analog ground pin serves as small-signal ground. All small-signal ground paths should connect to the
AGND pin and should also be electrically connected to power ground at a single point, avoiding any high
current ground returns.
4 FB Inverting input to the OTA error amplifier. The FB pin in conjunction with the external compensation serves to
stabilize and achieve the desired output voltage with current mode compensation.
5 COMP The loop compensation pin is used to compensate the transconductance amplifier which stabilizes the
operation of the converter stage. Place compensation components as close to the converter as possible.
Connect a RC network between COMP and AGND to compensate the control loop.
6 EN Enable pin. Pull EN to logic high to enable the device. Pull EN to logic low to disable the device. Do not leave
it open.
7 PG Power good is an open drain 500 mA pull down indicating output voltage is within the power good window. If
the power good function is not used, it can be connected to the VSW node to reduce thermal resistance. Do
not connect PG to the VSW node if the application is turning on into pre-bias.
8 VSW The VSW pin is the connection of the drains of the internal N and P MOSFETS. At switch off, the inductor will
drive this pin below ground as the body diode and the NMOS conducts with a high dv/dt.
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Table 2. ABSOLUTE MAXIMUM RATINGS (measured vs. GND pin 3, unless otherwise noted)
Rating Symbol VMAX VMIN Unit
Main Supply Voltage Input VIN 20 −0.3 V
Voltage between PGND and AGND VPAG 0.3 −0.3 V
PWM Feedback Voltage FB6−0.3 V
Error Amplifier Voltage COMP 6 −0.3 V
Enable Voltage EN VIN + 0.3 V −0.3 V
PG Voltage PG VIN + 0.3 V −0.3 V
VSW to AGND or PGND VSW VIN + 0.3 V −0.7 V
VSW to AGND or PGND for 35ns VSWST VIN + 10 V −5 V
Junction Temperature (Note 1) TJ+150 °C
Operating Ambient Temperature Range TA−40 to +85 °C
Storage Temperature Range Tstg − 55 to +150 °C
Thermal Characteristics (Note 2)
SOIC−8 Plastic Package
Maximum Power Dissipation @ TA = 25°C
Thermal Resistance Junction-to-Air
Thermal Resistance Junction-to-Case
PD
RqJA
RqJC
1.15
87
37.8
W
°C/W
°C/W
Lead Temperature Soldering (10 sec):
Reflow (SMD Styles Only) Pb-Free (Note 3) RF 260 peak °C
Stresses exceeding those listed in the Maximum Ratings table may damage the device. If any of these limits are exceeded, device functionality
should not be assumed, damage may occur and reliability may be affected.
1. The maximum package power dissipation limit must not be exceeded.
PD+
TJ(max)*TA
RqJA
2. The value of qJA is measured with the device mounted on 2in x 2in FR−4 board with 2oz. copper, in a still air environment with TA=25°C.
The value in any given application depends on the user’s specific board design.
3. 60−180 seconds minimum above 237°C.
Table 3. RECOMMENDED OPERATING CONDITIONS
Rating Symbol Min Max Unit
Main Supply Voltage Input VIN 4.5 18 V
Power Good Pin Voltage PG 0 18 V
Switch Pin Voltage VSW −0.3 18 V
Enable Pin Voltage EN 0 18 V
Comp Pin Voltage COMP −0.1 5.5 V
Feedback Pin Voltage FB −0.1 5.5 V
Power Ground Pin Voltage PGND −0.1 −0.1 V
Junction Temperature Range TJ−40 125 °C
Operating Temperature Range TA−40 85 °C
Functional operation above the stresses listed in the Recommended Operating Ranges is not implied. Extended exposure to stresses beyond
the Recommended Operating Ranges limits may affect device reliability.
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Table 4. ELECTRICAL CHARACTERISTICS
(TA = 25°C, VIN = VEN = 12 V, VOUT = 3.3 V for min/max values unless otherwise noted (Note 7))
Characteristic Conditions Min Typ Max Unit
Input Voltage Range (Note 5) 4.5 − 18 V
SUPPLY CURRENT
Quiescent Supply Current NCP3170A
NCP3170B VIN = EN = 12 V VFB = 0.8 V
(Note 5)
1.7
1.7 2.0
2.0 mA
Shutdown Supply Current EN = 0 V (Note 5) 13 17 mA
UNDER VOLTAGE LOCKOUT
VIN UVLO Threshold VIN Rising Edge (Note 5) − 4.41 V
VIN UVLO Threshold VIN Falling Edge (Note 5) − 4.13 V
MODULATOR
Oscillator Frequency NCP3170A
NCP3170B Enable = VIN 450
900 500
1000 550
1100 kHz
Maximum Duty Ratio NCP3170A
NCP3170B 91
90
96
96 %
Minimum Duty Ratio NCP3170A
NCP3170B VIN = 12 V 6.0
4.0
11
11.5 %
VIN Soft Start Ramp Time VFB = VCOMP 3.5 4.6 6.0 ms
OVER CURRENT
Current Limit (Note 4) 4.0 − 6.0 A
PWM COMPENSATION
VFB Feedback Voltage TA = 25°C 0.792 0.8 0.808 V
Line Regulation (Note 4) 1 − %
GM − 201 − mS
AOL DC gain (Note 4) 40 55 dB
Unity Gain BW (COUT = 10 pF) (Note 4) 2.0 − MHz
Input Bias Current (Current Out of FB IB Pin) (Note 4) 286 nA
IEAOP Output Source Current VFB = 0 V − 20.1 mA
IEAOM Output Sink Current VFB = 2 V − 21.3 − mA
ENABLE
Enable Threshold (Note 5) − 1.41 V
POWER GOOD
Power Good High On Threshold − 875 − mV
Power Good High Off Threshold − 859 − mV
Power Good Low On Threshold − 712 − mV
Power Good Low Off Threshold − 728 − mV
Over Voltage Protection Threshold − 998 − mV
Power Good Low Voltage VIN = 12 V, IPG = 500 mA− 0.195 V
PWM OUTPUT STAGE
High-Side Switch On-Resistance VIN = 12 V
VIN = 4.5 V
90
100 130
150 mW
Low-Side Switch On-Resistance VIN = 12 V
VIN = 4.5 V
25
29 35
39 mW
THERMAL SHUTDOWN
Thermal Shutdown (Notes 4 and 6) − 164 − °C
Hysteresis − 43 °C
Product parametric performance is indicated in the Electrical Characteristics for the listed test conditions, unless otherwise noted. Product
performance may not be indicated by the Electrical Characteristics if operated under different conditions.
4. Guaranteed by design
5. Ambient temperature range of −40°C to +85°C.
6. This is not a protection feature.
7. The device is not guaranteed to operate beyond the maximum operating ratings.
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TYPICAL PERFORMANCE CHARACTERISTICS
(Circuit from Figure 1, TA = 25°C, VIN = VEN = 12 V, VOUT = 3.3 V unless otherwise specified)
Figure 3. Light Load (DCM) Operation 1 ms/DIV Figure 4. Full Load (CCM) Operation 1 ms/DIV
Figure 5. Start−Up into Full Load 1 ms/DIV Figure 6. Short−Circuit Protection 200 ms /DIV
Figure 7. 50% to 100% Load Transient 100 ms/DIV Figure 8. 3.3 V Turn on into 1 V Pre−Bias 1 ms /DIV
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TYPICAL PERFORMANCE CHARACTERISTICS
(Circuit from Figure 1, TA = 25°C, VIN = VEN = 12 V, VOUT = 3.3 V unless otherwise specified)
Figure 9. ICC Shut Down Current vs.
Temperature Figure 10. NCP3170 Enabled Current vs.
Temperature
TEMPERATURE (°C) TEMPERATURE (°C)
11090703010−10−30−50
0
3
9
12
18
21
27
30
11090705010−10−30−50
1.3
1.4
1.5
1.6
1.7
1.9
2.0
2.1
Figure 11. Bandgap Reference Voltage vs.
Temperature Figure 12. Switching Frequency vs.
Temperature
TEMPERATURE (°C) TEMPERATURE (°C)
11070503010−10−30−50
797
798
799
801
802
804
805
806
11090703010−10−30−50
496
497
498
499
500
501
502
503
Figure 13. Input Under Voltage Protection at
12 V vs. Temperature Figure 14. Input Over Voltage Protection at
12 V vs. Temperature
TEMPERATURE (°C) TEMPERATURE (°C)
11090703010−10−30−50
705
710
715
720
725
730
735
11090703010−10−30−50
855
860
865
870
875
880
CURRENT DRAW (mA)
CURRENT DRAW (mA)
BANDGAP REFERENCE (mV)
SWITCHING FREQUENCY (kHz)
TRIP VOLTAGE AT FB PIN (mV)
TRIP VOLTAGE AT FB PIN (mV)
50 130
6
15
24 Input Voltage = 18 V
Input Voltage = 12 V
Input Voltage = 4.5 V
30
1.8
130
Input Voltage = 18 V
Input Voltage = 12 V
Input Voltage = 4.5 V
800
803
90 130
Input Voltage = 18 V
Input Voltage = 12 V
Input Voltage = 4.5 V
50 130
Input Voltage = 18 V
Input Voltage = 12 V
Input Voltage = 4.5 V
50 130
Under Voltage Protection Rising
Under Voltage Protection Falling
50 130
Over Voltage Protection Rising
Over Voltage Protection Falling
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TYPICAL PERFORMANCE CHARACTERISTICS
(Circuit from Figure 1, TA = 25°C, VIN = VEN = 12 V, VOUT = 3.3 V unless otherwise specified)
Figure 15. High Side MOSFET RDS(on) vs.
Temperature Figure 16. Low Side MOSFET RDS(on) vs.
Temperature
TEMPERATURE (°C) TEMPERATURE (°C)
11090503010−10−30−50
60
70
80
90
100
110
130
11090703010−10−30−50
15
20
25
30
35
40
Figure 17. Transconductance vs. Temperature Figure 18. Over Voltage Protection vs.
Temperature
TEMPERATURE (°C) TEMPERATURE (°C)
11090703010−10−30−50
180
185
190
195
200
205
210
215
11090703010−10−30−50
996.5
997.0
998.0
998.5
999.0
1000.0
1001.0
1001.5
HIGH SIDE MOSFET RDS(on) (mW)
LOW SIDE MOSFET RDS(on) (mW)
TRANSCONDUCTANCE (mS)
TRIP VOLTAGE AT FB PIN (mV)
70 130
Input Voltage = 12 V, 18 V
Input Voltage = 4.5 V
50 130
Input Voltage = 4.5 V
50 130
Input Voltage = 18 V
Input Voltage = 12 V
Input Voltage = 4.5 V
50 130
997.5
999.5
1000.5
Input Voltage = 18 V
Input Voltage = 12 V
Input Voltage = 4.5 V
Input Voltage = 12 V, 18 V
120
Figure 19. Input Under Voltage Protection vs.
Temperature
TRIP VOLTAGE AT FB PIN (mV)
Input Under Voltage Protection Rising
TEMPERATURE (°C)
Input Under Voltage Protection Falling
11090703010−10−30−50
4.05
4.10
4.15
4.20
4.25
4.30
4.35
4.45
50 130
4.40
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NCP3170A Efficiency and Thermal Derating
Figure 20. Efficiency (VIN = 12 V) vs. Load
Current Figure 21. Efficiency (VIN = 5 V) vs. Load Curren
t
0
10
20
30
40
50
60
70
80
90
100
12 V, 500 kHz
Efficiency
0123
OUTPUT CURRENT (A)
EFFICIENCY (%)
Vo = 1.2 V
Vo = 1.8 V Vo = 3.3 V Vo = 5 V
0
10
20
30
40
50
60
70
80
90
100
0123
OUTPUT CURRENT (A)
EFFICIENCY (%)
5 V, 500 kHz
Efficiency
Vo = 3.3 VVo = 1.8 V
Vo = 1.2 V
Thermal derating curves for the SOIC−8 package part under typical input and output conditions based on the evaluation board.
The ambient temperature is 25°C with natural convection (air speed < 50 LFM) unless otherwise specified.
Figure 22. 500 kHz Derating Curves at 5 V
0
1
2
3
4
5
25 35 45 55 65 75 85
TA, AMBIENT TEMPERATURE (°C)
IOUT, AMBIENT TEMPERATURE (°C)
1.2 V, 1.8 V,
3.3 V
0
1
2
3
4
5
25 35 45 55 65 75 85
Figure 23. 500 kHz Derating Curves at 12 V
TA, AMBIENT TEMPERATURE (°C)
1.2 V, 1.8 V,
3.3 V, 5.0 V
IOUT, AMBIENT TEMPERATURE (°C)
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NCP3170B Efficiency and Thermal Derating
Figure 24. 12 V, 1 MHz Efficiency Figure 25. 5 V, 1 MHz Efficiency
0
10
20
30
40
50
60
70
80
90
100
12 V, 1 MHz
Efficiency
0123
OUTPUT CURRENT (A)
EFFICIENCY (%)
Vo = 1.2 V
Vo = 1.8 V
Vo = 3.3 V Vo = 5 V
0
10
20
30
40
50
60
70
80
90
100
0123
OUTPUT CURRENT (A)
EFFICIENCY (%)
5 V, 1 MHz
Efficiency
Vo = 3.3 VVo = 1.8 V
Vo = 1.2 V
Thermal derating curves for the SOIC−8 package part under typical input and output conditions based on the evaluation board.
The ambient temperature is 25°C with natural convection (air speed < 50 LFM) unless otherwise specified.
Figure 26. 1 MHz Derating Curves at 5 V Input Figure 27. 1 MHz Derating Curves at 12 V Input
0
1
2
3
4
5
25 35 45 55 65 75 85
IOUT, AMBIENT TEMPERATURE (°C)
1.2 V,
1.8 V
3.3 V
TA, AMBIENT TEMPERATURE (°C) TA, AMBIENT TEMPERATURE (°C)
0
1
2
3
4
5
25 35 45 55 65 75 85
1.2 V,
1.8 V
3.3 V
5.0 V
IOUT, AMBIENT TEMPERATURE (°C)
voltage range. Features include enable control, PowerrOn Reset (FOR). input under voltage lockout, fixed internal soft start, power good indication, over voltage protection, and thermal shutdown. Enable and Salt-Start An internal input voltage comparator not shown in Figure 28 will force the part to disable below the minimum input voltage of 4.13 V. The input under voltage disable feature is used to prevent improper operation of the converter due to insufficient voltages. The converter can be Iumed on by tying the enable pin high and the part will default to be input voltage enabled. The enahle pin should never be left tloating. 45 V45 V ViN o— EN {b NCP3170 Figure 28. Input Voltage Enable 11‘ an adjustable Under Voltage Lockout (UVLO) threshold is required, the EN pin can he used. The trip voltage of the EN pin comparator is 1.38 V typical. Upon application of an input voltage greater than 4.41 \L the VIN UVLO will release and the enable will be checked to determine if Witching can commence. Once the 1.3x v trip voltage is cro 'ed, the pan will enable and the soft stan sequence will initiate. If large resistor values are used, the EN pin should be byp d with a l nF capacitor to prevent coupling problems from the switch node. 45 V45 V ViN of C I W EN NCP3170 Rluv '— 33 ’z" < ciuv="" figure="" 29.="" input="" under="" voltage="" lockout="" enable="" v5:="" figure="" 30="" hfi="" l="" i="" g:="" b="" figure="" 31.="" added="" hyster="" www.onsemi.com="" 1d="">
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DETAILED DESCRIPTION
The NCP3170 is a current-mode, step down regulator
with an integrated high-side PMOS switch and a low-side
NMOS switch. It operates from a 4.5 V to 18 V input voltage
range and supplies up to 3 A of load current. The duty ratio
can be adjusted from 8% to 92% allowing a wide output
voltage range. Features include enable control, Power-On
Reset (POR), input under voltage lockout, fixed internal soft
start, power good indication, over voltage protection, and
thermal shutdown.
Enable and Soft-Start
An internal input voltage comparator not shown in
Figure 28 will force the part to disable below the minimum
input voltage of 4.13 V. The input under voltage disable
feature is used to prevent improper operation of the
converter due to insufficient voltages. The converter can be
turned on by tying the enable pin high and the part will
default to be input voltage enabled. The enable pin should
never be left floating.
Figure 28. Input Voltage Enable
NCP3170
EN
VIN
AGND
4.5 V−18 V
C1IN
If an adjustable Under Voltage Lockout (UVLO)
threshold is required, the EN pin can be used. The trip
voltage of the EN pin comparator is 1.38 V typical. Upon
application of an input voltage greater than 4.41 V, the VIN
UVLO will release and the enable will be checked to
determine if switching can commence. Once the 1.38 V trip
voltage is crossed, the part will enable and the soft start
sequence will initiate. If large resistor values are used, the
EN pin should be bypassed with a 1 nF capacitor to prevent
coupling problems from the switch node.
Figure 29. Input Under Voltage Lockout Enable
NCP3170
EN
VIN
AGND
4.5 V−18 V
C1IN
R1UV
R2UV
C1UV
The enable pin can be used to delay a turn on by
connecting a capacitor as shown in Figure 30.
Figure 30. Delay Enable
NCP3170
EN
VIN
AGND
4.5 V−18 V
C1IN
Rbias
C1DLY
If the designer would like to add hysteresis to the enable
threshold it can be added by use of a bias resistor to the
output. The hysteresis is created once soft start has initiated.
With the output voltage rising, current flows into the enable
node, raising the voltage. The thresholds for enable as well
as hysteresis can be calculated using Equation 1.
VINHYS +VINStart *ENTH )R1UV
(eq. 1)
ƪVOUT *ENTH
R3UV *ENTH
R2UVƫ
V
INStart +ENTH ƪ1)R1UV ǒR2UV )R3UVǓ
R2UV R3UV ƫ(eq. 2
)
where:
ENTH = Enable Threshold
VINSTART = Input Voltage Start Threshold
R1UV = High Side Resistor
R2UV = Low Side Resistor
R3UV = Hysteresis Bias Resistor
VOUT = Regulated Output Voltage
Figure 31. Added Hysteresis to the Enable UVLO
NCP3170
EN
VIN
AGND
4.5 V−18 V
C1IN
R1UV
R2UV
R3UV
VOUT
He? 9 Figure 32. L ; vsw EN PG {E NCPZWO f; if ; vsw EN l— {E NCPZWO Figure 33. Enable Two Convener Power Se Once the part is enabled, the internal reference voltage is slewed from ground lo the set point of 800 mV. The slewing process occurs over a 4.5 ms period, reducing the currem draw from the upstream power source, reducing sti ss on internal MOSFETS, and ensuring the output inductor does not saturate during starlrup, Pre-Bias Siari-up When starting into a prerbias loadr the NCP3170 will not discharge the output capacitor. . The soft start begins with the internal reference at ground. Both the high side switch and low side switches are turned off, The internal reference www.0nsemi.com ll ELF? |:| Figure 34. 00V and DUV System
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The part can be enabled with standard TTL or high voltage
logic by using the configuration below.
Figure 32. Logic Turn-on
NCP3170
EN
VIN
AGND
4.5 V−18 V
C1IN
R1LOG
R2LOG C1LOG
The enable can also be used for power sequencing in
conjunction with the Power Good (PG) pin as shown in
Figure 33. The enable pin can either be tied to the output
voltage of the master voltage or tied to the input voltage with
a resistor to the PG pin of the master regulator.
Figure 33. Enable Two Converter Power Sequencing
NCP3170
EN
VIN
AGND
4.5 V−18 V
PG
VSW
FB
Vo1
Vo1
NCP3170
EN
VIN
AGND
4.5 V−18 V
VSW
FB
Vo2
Vo2
Once the part is enabled, the internal reference voltage is
slewed from ground to the set point of 800 mV. The slewing
process occurs over a 4.5 ms period, reducing the current
draw from the upstream power source, reducing stress on
internal MOSFETS, and ensuring the output inductor does
not saturate during start-up.
Pre-Bias Start-up
When starting into a pre-bias load, the NCP3170 will not
discharge the output capacitors. The soft start begins with
the internal reference at ground. Both the high side switch
and low side switches are turned off. The internal reference
slowly raises and the OTA regulates the output voltage to the
divided reference voltage. In a pre-biased condition, the
voltage at the FB pin is higher than the internal reference
voltage, so the OTA will keep the COMP voltage at ground
potential. As the internal reference is slewed up, the COMP
pin is held low until the FB pin voltage surpasses the internal
reference voltage, at which time the COMP pin is allowed
to respond to the OTA error signal. Since the bottom of the
PWM ramp is at 0.6 V there will be a slight delay between
the time the internal reference voltage passes the FB voltage
and when the part starts to switch. Once the COMP error
signal intersects with the bottom of the ramp, the high side
switch is turned on followed by the low side switch. After the
internal reference voltage has surpassed the FB voltage, soft
start proceeds normally without output voltage discharge.
Power Good
The output voltage of the buck converter is monitored at
the feedback pin of the output power stage. Two
comparators are placed on the feedback node of the OTA to
monitor the operating window of the feedback voltage as
shown in Figure 34. All comparator outputs are ignored
during the soft start sequence as soft start is regulated by the
OTA since false trips would be generated. Further, the PG
pin is held low until the comparators are evaluated. PG state
does not affect the switching of the converter. After the soft
start period has ended, if the feedback is below the reference
voltage of comparator 1 (VFB < 0.726), the output is
considered operational undervoltage (OUV). The device
will indicate the under voltage situation by the PG pin
remaining low with a 100 kW pull-up resistance. When the
feedback pin voltage rises between the reference voltages of
comparator 1 and comparator 2 (0.726 < VFB < 0.862),
then the output voltage is considered power good and the PG
pin is released. Finally, if the feedback voltage is greater than
comparator 2 (VFB > 0.862), the output voltage is
considered operational overvoltage (OOV). The OOV will
be indicated by the PG pin remaining low. A block diagram
of the OOV and OUV functionality as well as a graphical
representation of the PG pin functionality is shown in
Figures 34 through 36.
Figure 34. OOV and OUV System
FB 800 mV
862 mV
726 mV
Comp 2
Comp 1
SOFT
Start
Complete PG
12 V
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+
+
+
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Figure 35. OOV and OUV Window
VOOV = 862 mV
VOUV = 726 mV
VREF = 0.8 V
Hysteresis = 14 mV
Hysteresis = 14 mV Power Good
OUV
OOV
Figure 36. OOV and OUV Diagram
0.862 V
0.8 V
0.726 V
FB Voltage
Soft Start Complete
Power Good
If the power good function is not used, it can be connected
to the VSW node to reduce thermal resistance. Do not
connect PG to the VSW node if the application is turning on
into pre-bias.
Switching Frequency
The NCP3170 switching frequency is fixed and set by an
internal oscillator. The practical switching frequency could
range from 450 kHz to 550 kHz for the NCP3170A and
900 kHz to 1.1 MHz for the NCP3170B due to device
variation.
Light Load Operation
Light load operation is generally a load that is 1 mA to
300 mA where a load is in standby mode and requires very
little power. During light load operation, the regulator
emulates the operation of a non-synchronous buck converter
and the regulator is allowed to skip pulses. The
non-synchronous buck emulation is accomplished by
detecting the point at which the current flowing in the
inductor goes to zero and turning the low side switch off. At
the point when the current goes to zero, if the low side switch
is not turned off, current would reverse, discharging the
output capacitor. Since the low side switch is shutoff, the
only conduction path is through the body diode of the low
side MOSFET, which is back biased. Unlike traditional
synchronous buck converters, the current in the inductor
will become discontinuous. As a result, the switch node will
oscillate with the parasitic inductances and capacitances
connected to the switch node. The OTA will continue to
regulate the output voltage, but will skip pulses based on the
output load shown in Figure 37.
The quiescent supply current of the NCP3170 varies from
1.7 mA typically to 2 mA maximum. The variation in
inductance, capacitance, and resistance, and supply current
typically results in a light load efficiencies variation of 3%.
Zero Current Point
Switch
Node
0V
Inductor
Current
F
eedback
Voltage Reference Votlage
COMP
Voltage Ramp Threshold
0A
Figure 37. Light Load Operation
6
m
s = 166 kHz
2 ms = 50 kHz
PROTECTION FEATURES
Over Current Protection
Current is limited to the load on a pulse by pulse basis.
During each high side on period, the current is compared
against an internally set limit. If the current limit is
exceeded, the high side and low side MOSFETS are shutoff
and no pulses are issued for 13.5 ms. During that time, the
output voltage will decay and the inductor current will
discharge. After the discharge period, the converter will
initiate a soft start. If the load is not released, the current will
build in the inductor until the current limit is exceeded, at
which time the high side and low side MOSFETS will be
shut off and the process will continue. If the load has been
released, a normal soft start will commence and the part will
continue switching normally until the current limit is
exceeded.
S
witch
Node
I
nductor
Current
C
urrent Limit
Figure 38. Over Current Protection
13.5 ms Hold Time
The current limit has a positives voltage influence where
the peak current trip level increases 0.2%/V from the 5 V trip
level.
e lhetmal limit, while not a proteclicln feature. engages e of Iherm When the thermal r is tripped at a die temperature of150°C. the pan t cool to 120°C before a teslan is allowed. When Ihermal ttip is engaged, switching ceases and high side and low side ETs are driven off. Further, the power good indicalor will pull low until the thermal ttip has been released. Once temperatute reach e part will reinitiate sofirstan and begin nonna n Ihe complelion of soft stan, the output voltage of the utpul power stage. One comparator is placed on the feedback nude ent an over e is detected, the high side switch turns off and Ihe low tnge falls below has fallen below the Gov threshcld, switehing continues nonnally as displayed Input Volt-Kc (v) Innu! Voluae (VI 20 22 20 18 16 14 12 ll) w. o "1 w Over Maximum Input Voltage VWQN new SalereratirlgAvea u N UnderVultage swamuswuv «an mmmm autpmvalugt (v) Over Maxlmum Input Voltage Safe Operating Area Under Voltage “stew. <><><>< tn="">
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Thermal Shutdown
The thermal limit, while not a protection feature, engages
at 150°C in case of thermal runaway. When the thermal
comparator is tripped at a die temperature of 150°C, the part
must cool to 120°C before a restart is allowed. When thermal
trip is engaged, switching ceases and high side and low side
MOSFETs are driven off. Further, the power good indicator
will pull low until the thermal trip has been released. Once
the die temperature reaches 120°C the part will reinitiate
soft-start and begin normal operation.
Switch
Node
Output
Voltage
Thermal
Comparator
IC
Temperature
Figure 39. Over Temperature Shutdown
120°C
150°C
Over Voltage Protection
Upon the completion of soft start, the output voltage of the
buck converter is monitored at the FB pin of the output
power stage. One comparator is placed on the feedback node
to provide over voltage protection. In the event an over
voltage is detected, the high side switch turns off and the low
side switch turns on until the feedback voltage falls below
the OOV threshold. Once the voltage has fallen below the
OOV threshold, switching continues normally as displayed
in Figure 40.
0.800 V
0.726 V
0.862 V
FB Voltage
Power
Softstart
1.0 V
Low Side
Figure 40. Over Voltage Low Side Switch Behavior
Complete
Good
Switch
Duty Ratio
The duty ratio can be adjusted from 8% to 92% allowing
a wide output voltage range. The low 8% duty ratio limit will
restrict the PWM operation. For example if the application
is converting to 1.2 V the converter will perform normally
if the input voltage is below 15.5 V. If the input voltage
exceeds 15.5 V while supplying 1.2 V output voltage the
converter can skip pulses during operation. The skipping
pulse operation will result in higher ripple voltage than when
operating in PWM mode. Figure 41 and 42 below shows the
safe operating area for the NCP3170A and B respectively.
While not shown in the safe operating area graph, the output
voltage is capable of increasing to the 93% duty ratio
limitation providing a high output voltage such as 16 V. If
the application requires a high duty ratio such as converting
from 14 V to 10 V the converter will operate normally until
the maximum duty ratio is reached. For example, if the input
voltage were 16 V and the user wanted to produce the
highest possible output voltage at full load, a good rule of
thumb is to use 80% duty ratio. The discrepancy between the
usable duty ratio and the actual duty ratio is due to the
voltage drops in the system, thus leading to a maximum
output voltage of 12.8 V rather than 14.8 V. The actual
achievable output to input voltage ratio is dependent on
layout, component selection, and acceptable output voltage
tolerance.
Figure 41. NCP3170A Safe Operating Area
Figure 42. NCP3170B Safe Operating Area
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Design Procedure
When starting the design of a buck regulator, it is important
to collect as much information as possible about the behavior
of the input and output before starting the design.
ON Semiconductor has a Microsoft Excel® based design
tool available online under the design tools section of the
NCP3170 product page. The tool allows you to capture your
design point and optimize the performance of your regulator
based on your design criteria.
Table 5. DESIGN PARAMETERS
Design Parameter Example Value
Input Voltage (VIN)9 V to 16 V
Output Voltage (VOUT)3.3 V
Input Ripple Voltage (VCCRIPPLE)200 mV
Output Ripple Voltage (VOUTRIPPLE)20 mV
Output Current Rating (IOUT)3 A
Operating Frequency (FSW)500 kHz
The buck converter produces input voltage (VIN) pulses
that are LC filtered to produce a lower DC output voltage
(VOUT). The output voltage can be changed by modifying
the on time relative to the switching period (T) or switching
frequency. The ratio of high side switch on time to the
switching period is called duty ratio (D). Duty ratio can also
be calculated using VOUT, VIN, the Low Side Switch Voltage
Drop (VLSD), and the High Side Switch Voltage Drop
(VHSD).
FSW +1
T(eq. 3)
D+TON
T(1*D)+TOFF
T(eq. 4)
D+VOUT )VLSD
VIN *VHSD )VLSD [
(eq. 5)
D+VOUT
VIN ³27.5% +3.3 V
12 V
where:
D = Duty ratio
FSW = Switching frequency
T = Switching period
TOFF = High side switch off time
TON = High side switch on time
VIN = Input voltage
VHSD = High side switch voltage drop
VLSD = Low side switch voltage drop
VOUT = Output voltage
Inductor Selection
When selecting an inductor, the designer may employ
a rule of thumb for the design where the percentage of ripple
current in the inductor should be between 10% and 40%.
When using ceramic output capacitors, the ripple current can
be greater because the ESR of the output capacitor is smaller,
thus a user might select a higher ripple current. However,
when using electrolytic capacitors, a lower ripple current
will result in lower output ripple due to the higher ESR of
electrolytic capacitors. The ratio of ripple current to
maximum output current is given in Equation 6.
ra +DI
IOUT (eq. 6)
where:
ąDI = Ripple current
IOUT = Output current
ra = Ripple current ratio
Using the ripple current rule of thumb, the user can
establish acceptable values of inductance for a design using
Equation 6.
LOUT +VOUT
IOUT ra FSW (1*D)³
(eq. 7)
4.7 mH+3.3 V
3.0 A 34% 500 kHz (1*27.5%)
where:
D = Duty ratio
FSW = Switching frequency
IOUT = Output current
LOUT = Output inductance
ra = Ripple current ratio
4.7 mH
7 V
4.4 V
Figure 43. Inductance vs. Current Ripple Ratio
18 V
19
17
15
13
11
9
7
5
3
1
10 13 16 19 22 25 28 31 34 37 40
RIPPLE CURRENT RATIO (%)
INDUCTANCE (mH)
When selecting an inductor, the designer must not exceed
the current rating of the part. To keep within the bounds of
the part’s maximum rating, a calculation of the RMS current
and peak current are required.
CU: CU: CU:
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IRMS +IOUT 1)ra2
12
Ǹ³
(eq. 8)
3.01 A +3A 1)34%2
12
Ǹ³
where:
IOUT = Output current
IRMS = Inductor RMS current
ra = Ripple current ratio
IPK +IOUT ǒ1)ra
2Ǔ³
(eq. 9)
3.51 A +3A ǒ1)34%
2Ǔ
where:
IOUT = Output current
IPK = Inductor peak current
ra = Ripple current ratio
A standard inductor should be found so the inductor will
be rounded to 4.7 mH. The inductor should support an RMS
current of 3.01 A and a peak current of 3.51 A. A good
design practice is to select an inductor that has a saturation
current that exceeds the maximum current limit with some
margin.
The final selection of an output inductor has both
mechanical and electrical considerations. From a
mechanical perspective, smaller inductor values generally
correspond to smaller physical size. Since the inductor is
often one of the largest components in the regulation system,
a minimum inductor value is particularly important in space
constrained applications. From an electrical perspective, the
maximum current slew rate through the output inductor for
a buck regulator is given by Equation 10.
SlewRateLOUT +VIN *VOUT
LOUT ³
(eq. 10)
1.85 A
ms+12 V *3.3 V
4.7 mH
where:
LOUT = Output inductance
VIN = Input voltage
VOUT = Output voltage
Equation 10 implies that larger inductor values limit the
regulators ability to slew current through the output
inductor in response to output load transients. Consequently,
output capacitors must supply the load current until the
inductor current reaches the output load current level.
Reduced inductance to increase slew rates results in larger
values of output capacitance to maintain tight output voltage
regulation. In contrast, smaller values of inductance increase
the regulators maximum achievable slew rate and decrease
the necessary capacitance at the expense of higher ripple
current. The peak-to-peak ripple current for NCP3170 is
given by the following equation:
IPP +VOUT (1*D)
LOUT FSW ³
(eq. 11)
1.02 A +3.3 V (1*27.5%)
4.7 mH 500 kHz
where:
D = Duty ratio
FSW = Switching frequency
IPP = Peak-to-peak current of the inductor
LOUT = Output inductance
VOUT = Output voltage
From Equation 11, it is clear that the ripple current
increases as LOUT decreases, emphasizing the trade-off
between dynamic response and ripple current.
The power dissipation of an inductor falls into two
categories: copper and core losses. Copper losses can be
further categorized into DC losses and AC losses. A good
first order approximation of the inductor losses can be made
using the DC resistance as shown below:
LPCU_DC +IRMS 2 DCR ³(eq. 12)
61 mW +3.012 6.73 mW
where:
DCR = Inductor DC resistance
IRMS = Inductor RMS current
LPCU_DC = Inductor DC power dissipation
The core losses and AC copper losses will depend on the
geometry of the selected core, core material, and wire used.
Most vendors will provide the appropriate information to
make accurate calculations of the power dissipation at which
point the total inductor losses can be captured by the
equation below:
LPtot +LPCU_DC )LPCU_AC )LPCore ³(eq. 13)
67 mW +61 mW )5mW)1mW
where:
LPCore = Inductor core power dissipation
LPCU_AC = Inductor AC power dissipation
LPCU_DC = Inductor DC power dissipation
LPtot = Total inductor losses
Output Capacitor Selection
The important factors to consider when selecting an
output capacitor are DC voltage rating, ripple current rating,
output ripple voltage requirements, and transient response
requirements.
The output capacitor must be able to operate properly for
the life time of a product. When selecting a capacitor it is
important to select a voltage rating that is de-rated to the
guaranteed operating life time of a product. Further, it is
important to note that when using ceramic capacitors, the
capacitance decreases as the voltage applied increases; thus
a ceramic capacitor rated at 100 mF 6.3 V may measure
100 mF at 0 V but measure 20 mF with an applied voltage of
3.3 V depending on the type of capacitor selected.
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The output capacitor must be rated to handle the ripple
current at full load with proper derating. The capacitor RMS
ratings given in datasheets are generally for lower switching
frequencies than used in switch mode power supplies, but a
multiplier is given for higher frequency operation. The RMS
current for the output capacitor can be calculated below:
CORMS +IOUT ra
12
Ǹ³
(eq. 14)
0.294 A +3.0 A 34%
12
Ǹ
where:
CoRMS = Output capacitor RMS current
IOUT = Output current
ra = Ripple current ratio
The maximum allowable output voltage ripple is a
combination of the ripple current selected, the output
capacitance selected, the Equivalent Series Inductance
(ESL), and Equivalent Series Resistance (ESR).
The main component of the ripple voltage is usually due
to the ESR of the output capacitor and the capacitance
selected, which can be calculated as shown in Equation 14:
VESR_C +IOUT ra ǒCOESR )1
8 FSW COUTǓ³
(eq. 15)
10.89 mV +3 34% ǒ5mW)1
8 500 kHz 44 mFǓ
where:
CoESR = Output capacitor ESR
COUT = Output capacitance
FSW = Switching frequency
IOUT = Output current
ra = Ripple current ratio
VESR_C = Ripple voltage from the capacitor
The impedance of a capacitor is a function of the
frequency of operation. When using ceramic capacitors, the
ESR of the capacitor decreases until the resonant frequency
is reached, at which point the ESR increases; therefore the
ripple voltage might not be what one expected due to the
switching frequency. Further, the method of layout can add
resistance in series with the capacitance, increasing ripple
voltage.
The ESL of capacitors depends on the technology chosen,
but tends to range from 1 nH to 20 nH, where ceramic
capacitors have the lowest inductance and electrolytic
capacitors have the highest. The calculated contributing
voltage ripple from ESL is shown for the switch on and
switch off below:
VESLON +ESL IPP FSW
D³(eq. 16)
1.84 mV +1nH@1.01 A @500 kHz
27.5%
VESLOFF +ESL IPP FSW
(1*D)³(eq. 17)
0.7 mV +1nH 1.1 A 500 kHz
(1*27.5%)
where:
D = Duty ratio
ESL = Capacitor inductance
FSW = Switching frequency
IPP = Peak-to-peak current
The output capacitor is a basic component for fast
response of the power supply. For the first few microseconds
of a load transient, the output capacitor supplies current to
the load. Once the regulator recognizes a load transient, it
adjusts the duty ratio, but the current slope is limited by the
inductor value.
During a load step transient, the output voltage initially
drops due to the current variation inside the capacitor and the
ESR (neglecting the effect of the ESL).
DVOUTESR +ITRAN COESR ³(eq. 18)
7.5 mV +1.5 A 5mW
where:
CoESR = Output capacitor Equivalent Series
Resistance
ITRAN = Output transient current
ąDVOUT_ESR = Voltage deviation of VOUT due to the
effects of ESR
A minimum capacitor value is required to sustain the
current during the load transient without discharging it. The
voltage drop due to output capacitor discharge is given by
the following equation:
DVOUTDIS +ǒITRANǓ2 LOUT FSW
2 FCROSS COUT ǒVIN *VOUTǓ³
(eq. 19)
138.1 mV +(1.5)2 4.7 mH 500 kHz
2 50 kHz 44 mF ǒ12 V *3.3 VǓ
where:
COUT = Output capacitance
D = Duty ratio
FSW = Switching frequency
FCROSS = Loop cross over frequency
ITRAN = Output transient current
LOUT = Output inductor value
VIN = Input voltage
VOUT = Output voltage
ąDVOUT_DIS = Voltage deviation of VOUT due to the
effects of capacitor discharge
In a typical converter design, the ESR of the output
capacitor bank dominates the transient response. Please note
that DVOUT_DIS and DVOUT_ESR are out of phase with each
other, and the larger of these two voltages will determine the
Psw: RMS: RDS(ON):
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maximum deviation of the output voltage (neglecting the
effect of the ESL). It is important to note that the converters
frequency response will change when the NCP3170 is
operating in synchronous mode or non-synchronous mode
due to the change in plant response from CCM to DCM. The
effect will be a larger transient voltage excursion when
transitioning from no load to full load quickly.
Input Capacitor Selection
The input capacitor has to sustain the ripple current
produced during the on time of the upper MOSFET, so it
must have a low ESR to minimize losses and input voltage
ripple. The RMS value of the input ripple current is:
IinRMS +IOUT D (1*D)
Ǹ³(eq. 20)
1.34 A +3A 27.5% (1*27.5%)
Ǹ
where:
D = Duty ratio
IinRMS = Input capacitance RMS current
IOUT = Load current
The equation reaches its maximum value with D = 0.5 at
which point the input capacitance RMS current is half the
output current. Loss in the input capacitors can be calculated
with the following equation:
PCIN +CINESR ǒIinRMSǓ2
(eq. 21)
18 mW +10 mW ǒ1.34 AǓ2
where:
CINESR = Input capacitance Equivalent Series
Resistance
IinRMS = Input capacitance RMS current
PCIN = Power loss in the input capacitor
Due to large di/dt through the input capacitors, electrolytic
or ceramics should be used. If a tantalum capacitor must be
used, it must be surge protected, otherwise capacitor failure
could occur.
POWER MOSFET DISSIPATION
Power dissipation, package size, and the thermal
environment drive power supply design. Once the
dissipation is known, the thermal impedance can be
calculated to prevent the specified maximum junction
temperatures from being exceeded at the highest ambient
temperature.
Power dissipation has two primary contributors:
conduction losses and switching losses. The high-side
MOSFET will display both switching and conduction
losses. The switching losses of the low side MOSFET will
not be calculated as it switches into nearly zero voltage and
the losses are insignificant. However, the body diode in the
low-side MOSFET will suffer diode losses during the
non-overlap time of the gate drivers.
Starting with the high-side MOSFET, the power
dissipation can be approximated from:
PD_HS +PCOND )PSW_TOT (eq. 22)
where:
PCOND = Conduction losses
PD_HS = Power losses in the high side MOSFET
PSW_TOT = Total switching losses
The first term in Equation 21 is the conduction loss of the
high-side MOSFET while it is on.
PCOND +ǒIRMS_HSǓ2 RDS(on)_HS (eq. 23)
where:
IRMS_HS = RMS current in the high side MOSFET
RDS(ON)_HS = On resistance of the high side MOSFET
PCOND = Conduction power losses
Using the ra term from Equation 6, IRMS becomes:
IRMS_HS +IOUT D ǒ1)ra2
12Ǔ
Ǹ(eq. 24)
where:
D = Duty ratio
ra = Ripple current ratio
IOUT = Output current
IRMS_HS = High side MOSFET RMS current
The second term from Equation 22 is the total switching
loss and can be approximated from the following equations.
PSW_TOT +PSW )PDS )PRR (eq. 25)
where:
PDS = High side MOSFET drain to source losses
PRR = High side MOSFET reverse recovery
losses
PSW = High side MOSFET switching losses
PSW_TOT = High side MOSFET total switching losses
The first term for total switching losses from Equation 25
are the losses associated with turning the high-side
MOSFET on and off and the corresponding overlap in drain
voltage and current.
PSW +PTON )PTOFF +(eq. 26)
+1
2 ǒIOUT VIN FSWǓ ǒtRISE )tFALLǓ
where:
FSW = Switching frequency
IOUT = Load current
PSW = High side MOSFET switching losses
PTON = Turn on power losses
PTOFF = Turn off power losses
-VGS GATE-To-SOURCE VOLTAGE 0 2 4 s 5 Q“, TOTAL GATE CHARGE (n0)
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tFALL = MOSFET fall time
tRISE = MOSFET rise time
VIN = Input voltage
When calculating the rise time and fall time of the high
side MOSFET, it is important to know the charge
characteristic shown in Figure 44.
Figure 44. High Side MOSFET Total Charge
Vth
tRISE +QGD
IG1 +QGD
ǒVCL *VTHǓńǒRHSPU )RGǓ(eq. 27)
where:
IG1 = Output current from the high-side gate
drive
QGD = MOSFET gate to drain gate charge
RHSPU = Drive pull up resistance
RG= MOSFET gate resistance
tRISE = MOSFET rise time
VCL = Clamp voltage
VTH = MOSFET gate threshold voltage
tFALL +QGD
IG2 +QGD
ǒVCL *VTHǓńǒRHSPD )RGǓ(eq. 28)
where:
IG2 = Output current from the low-side gate
drive
QGD = MOSFET gate to drain gate charge
RG= MOSFET gate resistance
RHSPD = Drive pull down resistance
tFALL = MOSFET fall time
VCL = Clamp voltage
VTH = MOSFET gate threshold voltage
Next, the MOSFET output capacitance losses are caused
by both the high-side and low-side MOSFETs, but are
dissipated only in the high-side MOSFET.
PDS +1
2 COSS VIN 2 FSW (eq. 29)
where:
COSS = MOSFET output capacitance at 0 V
FSW = Switching frequency
PDS = MOSFET drain to source charge losses
VIN = Input voltage
Finally, the loss due to the reverse recovery time of the
body diode in the low−side MOSFET is shown as follows:
PRR +QRR VIN FSW (eq. 30)
where:
FSW = Switching frequency
PRR = High side MOSFET reverse recovery
losses
QRR = Reverse recovery charge
VIN = Input voltage
The low-side MOSFET turns on into small negative
voltages so switching losses are negligible. The low-side
MOSFET’s power dissipation only consists of conduction
loss due to RDS(on) and body diode loss during non-overlap
periods.
PD_LS +PCOND )PBODY (eq. 31)
where:
PBODY = Low side MOSFET body diode losses
PCOND = Low side MOSFET conduction losses
PD_LS = Low side MOSFET losses
Conduction loss in the low-side MOSFET is described as
follows:
PCOND +ǒIRMS_LSǓ2 RDS(on)_LS (eq. 32)
where:
IRMS_LS = RMS current in the low side
RDS(ON)_LS = Low-side MOSFET on resistance
PCOND = High side MOSFET conduction losses
IRMS_LS +IOUT (1*D) ǒ1)ra2
12Ǔ
Ǹ(eq. 33)
where:
D = Duty ratio
IOUT = Load current
IRMS_LS = RMS current in the low side
ra = Ripple current ratio
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The body diode losses can be approximated as:
PBODY +VFD IOUT FSW ǒNOLLH )NOLHLǓ(eq. 34)
where:
FSW = Switching frequency
IOUT = Load current
NOLHL = Dead time between the high-side
MOSFET turning off and the low-side
MOSFET turning on, typically 30 ns
NOLLH = Dead time between the low-side
MOSFET turning off and the high-side
MOSFET turning on, typically 30 ns
PBODY = Low-side MOSFET body diode losses
VFD = Body diode forward voltage drop
typically 0.92 V
Compensation Network
To create a stable power supply, the compensation
network around the transconductance amplifier must be
used in conjunction with the PWM generator and the power
stage. Since the power stage design criteria is set by the
application, the compensation network must correct the
overall output to ensure stability. The NCP3170 is a current
mode regulator and as such there exists a voltage loop and
a current loop. The current loop causes the inductor to act
like a current source which governs most of the
characteristics of current mode control. The output inductor
and capacitor of the power stage form a double pole but
because the inductor is treated like a current source in closed
loop, it becomes a single pole system. Since the feedback
loop is controlling the inductor current, it is effectively like
having a current source feeding a capacitor; therefore the
pole is controlled by the load and the output capacitance. A
table of compensation values for 500 kHz and 1 MHz is
provided below for two 22 mF ceramic capacitors. The table
also provides the resistor value for CompCalc at the defined
operating point.
Table 6. COMPENSATION VALUES
VIN
(V)
Vout
(V)
Lout
(mF)
R1
(kW)
R2
(kW)
Rf
(kW)
Cf
(pF)
Cc
(nF)
Rc
(kW)
Cp
(pF)
Resistance for
Current Gain
NCP3170A
12 0.8 1.8 24.9 NI NI NI NI NI 15 3.6
12 1.0 2.5 24.9 100 1 150 15 0.825 NI 4
12 1.1 2.5 24.9 66.5 1 150 10 2 NI 20
12 1.2 2.5 24.9 49.9 1 150 10 2 NI 20
12 1.5 3.6 24.9 28.7 1 150 10 2.49 NI 20
12 1.8 3.6 24.9 20 1 150 10 2.49 NI 20
12 2.5 4.7 24.9 11.8 1 150 8.2 3.74 NI 25
12 3.3 4.7 24.9 7.87 1 150 6.8 4.99 NI 27
12 5.0 7.2 24.9 4.75 1 150 3.9 10 NI 27
12 10.68 7.2 24.9 2.05 1 150 3.9 10 NI 30
18 14.8 7.2 24.9 1.43 1 150 6.8 6.98 NI 30
5 0.8 1.8 24.9 NI NI NI NI NI 15 15
5 1.0 2.5 24.9 100 1 150 15 0.825 NI 28
5 1.1 2.5 24.9 66.5 1 150 10 2 NI 30
5 1.2 2.5 24.9 49.9 1 150 10 2 NI 30
5 1.5 3.6 24.9 28.7 1 150 10 2.49 NI 30
5 1.8 3.6 24.9 20 1 150 10 2.49 NI 30
5 2.5 3.6 24.9 11.8 1 150 6.8 4.99 NI 50
5 3.3 3.6 24.9 7.87 1 150 6.8 4.99 NI 50
VI
NCP3170
www.onsemi.com
20
Table 6. COMPENSATION VALUES (continued)
Resistance for
Current Gain
Cp
(pF)
Rc
(kW)
Cc
(nF)
Cf
(pF)
Rf
(kW)
R2
(kW)
R1
(kW)
Lout
(mF)
Vout
(V)
VIN
(V)
NCP3170B
12 1.2 1.5 24.9 49.9 1 82 2.7 6.04 NI 20
12 1.5 1.8 24.9 28.7 1 82 2.7 6.04 NI 22
12 1.8 1.8 24.9 20 1 82 2.7 6.04 NI 22
12 2.5 2.7 24.9 11.8 1 82 1.8 10 NI 32
12 3.3 3.3 24.9 7.87 1 82 1.5 12.1 NI 52
12 5.0 3.3 24.9 4.75 1 82 2.2 8.25 NI 52
12 10.68 1.5 24.9 2.05 1 82 2.2 5.1 NI 52
18 14.8 3.3 24.9 1.43 1 82 2.2 5.1 NI 52
5 0.8 1.0 24.9 NI NI NI 15 0.499 NI 20
5 1.0 1.0 24.9 100 NI NI 6.8 1.69 NI 28
5 1.1 1.0 24.9 66.5 NI NI 3.9 3.61 NI 42
5 1.2 1.5 24.9 49.9 1 82 2.7 6.04 NI 55
5 1.5 1.5 24.9 28.7 1 82 2.7 6.04 NI 55
5 1.8 1.5 24.9 20 1 82 1.8 10 NI 55
5 2.5 1.8 24.9 11.8 1 82 1.8 10 NI 55
5 3.3 1.8 24.9 7.87 1 82 1.8 10 NI 55
To compensate the converter we must first calculate the
current feedback
M+
FSW LOUT VRAMP
RMAP VIN )1³(eq. 35)
6.299 +500 kHz 4.7 mH 0.33 V
ǒ32 3.3 V
12 V)1.46Ǔ
1000 W 12 V
)1
where:
FSW = Switching Frequency
LOUT = Output inductor value
M = Current feedback
Vin = Input Voltage
VOUT = Output Voltage
VRAMP = Slope Compensation Ramp
RMAP = Current Sense Resistance
The un-scaled gain of the converter also needs to be
calculated as follows:
A+1
IOUT
VOUT )
M*0.5*M VOUT
VIN
LOUT FSW (eq. 36)
0.379 W+1
3.0 A
3.3 V )
6.299*0.5*6.299 3.3 V
12 V
4.7 mH 500 kHz
where:
A = Un-scaled gain
FSW = Switching Frequency
IOUT = Output Current
LOUT = Output inductor value
M = Current feedback
VIN = Input Voltage
VOUT = Output Voltage
Next the DC gain of the plant must be calculated.
G+A
RMAP ³
(eq. 37)
36.925 +0.379 W
ǒ32 3.3 V
12 V)1.46Ǔ
1000 W
where:
G = DC gain of the plant
A = Un−scaled gain
The amplitude ratio can be calculated using the following
equation:
Y+VREF
VOUT ³0.242 +0.8 V
3.3 V (eq. 38)
where:
Vo = Output voltage
VREF = Regulator reference voltage
Y = Amplitude ratio
1 FF : W ” X X a” (ea, 40) 9.543 kHz : + 2.1 x 0.37912 >< 44hr:="" where:="" a="" una="" aled="" gain="" com="" output="" capacitor="" fr="Current" mode="" pole="" frequency="" the="" two="" equations="" above="" define="" the="" bode="" plot="" that="" the="" power="" stage="" has="" created="" or="" open="" loop="" response="" of="" the="" .="" em.="" the="" next="" step="" is="" to="" close="" the="" loop="" by="" considering="" the="" feedback="" valuel="" .="" the="" closed="" loop="" crossover="" frequency="" should="" be="" less="" than="" 1/10="" ofthe="" witching="" frequency,="" which="" would="" place="" the="" maximum="" cro="" over="" frequency="" at="" 50="" khz="" figure="" 45="" shows="" a="" pseudo="" type="" iii="" transconductance="" error="" amplifier.="" flgure="" 45.="" pseudo="" type="" iii="" ransconduclance="" error="" ampl="" the="" compensation="" network="" con="" s="" of="" the="" interim]="" enor="" amplifier="" and="" the="" inrpedance="" networks="" er="" (ri,="" rzl="" and="" cf)="" and="" external="" zn;="" (rc="" cc,="" and="" cf).="" the="" compensation="" network="" has="" to="" provtde="" a="" closed="" loop="" tra="" 'fel'="" function="" with="" the="" highel="" l="" response="" and="" the="" high="" to="" minimize="" load="" regulation="" i.="" uesrastable="" control="" loop="" ha="" again="" cro,="" ing="" with="" —20="" (ie/decade="" lope="" and="" a="" phase="" margin="" greater="" than="" 45°.="" include="" worstr="" se="" component="" variations="" when="" figure="" 46.="" feedba="" http://wwwonsemi="" .com/pub/collateral/compcalc="" .zlp="" www.0nsemi.com="" 21="">
NCP3170
www.onsemi.com
21
The ESR of the output capacitor creates a “zero” at the
frequency as shown in Equation 39:
FZESR +1
2p COESR COUT ³
(eq. 39)
723 kHz +1
2p 5mW 44 mF
where:
COESR = Output capacitor ESR
COUT = Output capacitor
FZESR = Output capacitor zero ESR frequency
FP+1
2p A COUT ³
(eq. 40)
9.548 kHz +1
2p 0.379 W 44 mF
where:
A = Un-scaled gain
COUT = Output capacitor
FP = Current mode pole frequency
The two equations above define the bode plot that the
power stage has created or open loop response of the system.
The next step is to close the loop by considering the feedback
values. The closed loop crossover frequency should be less
than 1/10 of the switching frequency, which would place the
maximum crossover frequency at 50 kHz.
Figure 45 shows a pseudo Type III transconductance error
amplifier.
Figure 45. Pseudo Type III Transconductance Error
Amplifier
ZFB
IEA
ZIN
R1
R2
VREF
RC
CC CP
CF
+
The compensation network consists of the internal error
amplifier and the impedance networks ZIN (R1, R2, and CF)
and external ZFB (RC, CC, and CP). The compensation
network has to provide a closed loop transfer function with
the highest 0 dB crossing frequency to have fast response
and the highest gain in DC conditions, so as to minimize load
regulation issues. A stable control loop has a gain crossing
with −20 dB/decade slope and a phase margin greater than
45°. Include worst-case component variations when
determining phase margin. To start the design, a resistor
value should be chosen for R1 from which all other
components can be chosen. A good starting value is 24.9 kW.
The NCP3170 allows the output of the DC−DC regulator
to be adjusted down to 0.8 V via an external resistor divider
network. The regulator will maintain 0.8 V at the feedback
pin. Thus, if a resistor divider circuit was placed across the
feedback pin to VOUT, the regulator will regulate the output
voltage proportional to the resistor divider network in order
to maintain 0.8 V at the FB pin.
Figure 46. Feedback Resistor Divider
R1
R2
FB
VOUT
The relationship between the resistor divider network
above and the output voltage is shown in Equation 41:
R2+R1 ǒVREF
VOUT *VREFǓ(eq. 41)
where:
R1= Top resistor divider
R2= Bottom resistor divider
VOUT = Output voltage
VREF = Regulator reference voltage
The most frequently used output voltages and their
associated standard R1 and R2 values are listed in the table
below.
Table 7. OUTPUT VOLTAGE SETTINGS
VO (V) R1 (kW) R2 (kW)
0.8 24.9 Open
1.0 24.9 100
1.1 24.9 66.5
1.2 24.9 49.9
1.5 24.9 28.7
1.8 24.9 20
2.5 24.9 11.8
3.3 24.9 8.06
5.0 24.9 4.64
The compensation components for the Pseudo Type III
Transconductance Error Amplifier can be calculated using
the method described below. The method serves to provide
a good starting place for compensation of a power supply.
The values can be adjusted in real time using the
compensation tool CompCalc
http://www.onsemi.com/pub/Collateral/COMPCALC.ZIP
27x H1+HZ
NCP3170
www.onsemi.com
22
The first pole to crossover at the desired frequency should
be setup at FPO to decrease at −20 dB per decade:
FPO +FCROSS
G³(eq. 42)
1.354 kHz +50 kHz
36.925 ³
where:
Fcross = Cross over frequency
FPO = Pole frequency to meet crossover
frequency
G = DC gain of the plant
The crossover combined compensation network can be
used to calculate the transconductance output compensation
network as follows:
CC+y gm
2 p FPO ³
(eq. 43)
5.70 nF +0.242 200 ms
2p 1.354 kHz
where:
CC= Compensation capacitor
FPO = Pole frequency
gm = Transconductance of amplifier
y = Amplitude ratio
RC+1
2p CC FP³
(eq. 44)
2.925 kW+1
2p 5.70 nF 1.354 kHz
where:
CC= Compensation capacitance
COUT = Output capacitance
FP = Current mode pole frequency
RC= Compensation resistor
CP+1
2p RC FESR ³
(eq. 45)
75.2 pF +1
2p 2.925 kW 723 kHz
where:
CP = Compensation pole capacitor
FESR = Capacitor ESR zero frequency
RC= Compensation resistor
If the ESR frequency is greater than the switching
frequency, a CF compensation capacitor may be needed for
stability as the output LC filter is considered high Q and thus
will not give the phase boost at the crossover frequency.
Further at low duty cycles due to some blanking and filtering
of the current signal the current gain of the converter is not
constant and the current gain is small. Thus adding CF and
RF can give the needed phase boost.
4
56 pF +24.9 kW)7.87 kW
2p (24.9 kW*1kW)7.87 kW*1kW)7.87 kW* 24.9 kW) 50 kHz
(eq. 46
)
CF+
R1
)
R2
2p (R1 * RF )R2 * RF )R2 * R1) Fcross ³
where:
CF= Compensation pole capacitor
Fcross = Cross over frequency
gm = Transconductance of amplifier
R1= Top resistor divider
R2= Bottom resistor divider
RF= Feed through resistor
Calculating Input Inrush Current
The input inrush current has two distinct stages: input
charging and output charging. The input charging of a buck
stage is usually controlled, but there are times when it is not
and is limited only by the input RC network, and the output
impedance of the upstream power stage. If the upstream
power stage is a perfect voltage source and switches on
instantaneously, then the input inrush current can be
depicted as shown in Figure 47 and calculated as:
IPK
Figure 47. Input Charge Inrush Current
IICinrush_PK1+VIN
CINESR (eq. 47)
1.2 kA +12
0.01
IICinrush_RMS1+VIN
CINESR 0.316 5 CINESR CIN
tDELAY_TOTAL
Ǹ
(eq. 48)
12.58 A +12 V
0.01 0.316 5 0.01 W 22 mF
1ms
Ǹ
cmmam current, Ihcn the J: /: Figure 48. Load Connecked to the Oukpuk Skage nse
NCP3170
www.onsemi.com
23
where:
CIN = Output capacitor
CINESR = Output capacitor ESR
tDELAY_TOTAL= Total delay interval
VIN = Input Voltage
Once the tDELAY_TOTAL has expired, the buck converter
starts to switch and a second inrush current can be
calculated:
IOCinrush_RMS +ǒCOUT )CLOADǓ VOUT
tSS
D
3
Ǹ)ICL D(eq. 49)
where:
COUT = Total converter output capacitance
CLOAD = Total load capacitance
D = Duty ratio of the load
ICL = Applied load at the output
IOCinrush_RMS = RMS inrush current during start-up
tSS = Soft start interval
VOUT = Output voltage
From the above equation, it is clear that the inrush current
is dependent on the type of load that is connected to the
output. Two types of load are considered in Figure 48: a
resistive load and a stepped current load.
Figure 48. Load Connected to the Output Stage
Inrush
Current
XCP3170
Load
OR
If the load is resistive in nature, the output current will
increase with soft start linearly which can be quantified in
Equation 50.
ICLR_RMS +1
3
Ǹ VOUT
ROUT (eq. 50)
ICR_PK +VOUT
ROUT
191 mA +1
3
Ǹ 3.3 V
10 W300 mA +3.3 V
10 W
where:
ICLR_RMS = RMS resistor current
ICR_PK = Peak resistor current
ROUT = Output resistance
VOUT = Output voltage
Figure 49. Resistive Load Current
Output
Voltage
Output
Current
3.3 V
tss
Alternatively, if the output load has an under voltage
lockout, turns on at a defined voltage level, and draws a
constant current, then the RMS connected load current is:
ICL1 +VOUT *VOUT_TO
VOUT
Ǹ IOUT
(eq. 51)
492 mA +3.3 V *2.5 V
3.3 V
Ǹ 1A
where:
IOUT = Output current
VOUT = Output voltage
VOUT_TO = Output voltage load turn on
Figure 50. Voltage Enable Load Current
Output
Voltage
Output
Current
tss
t
3.3 V1.0 V
If the inrush current is higher than the steady state input
current during max load, then an input fuse should be rated
accordingly using I2t methodology.
471 r E www.0nsemi.com 24
NCP3170
www.onsemi.com
24
THERMAL MANAGEMENT AND LAYOUT
Consideration
In the NCP3170 buck regulator high pulsing current flows
through two loops as shown in the figure below.
VIN
VIN VSW L1 4.7 mH
DRIVE R1
R2
C2, C3
22 mF
3.3 V
EN
PG
COMP
AGND PGND
FB1
Input
Current
C1
22 mFCbypass
0.1 mF
RC
CC
Figure 51. Buck Converter Current Paths
The first loop shown in blue activates when the high side
switch turns on. When the switch turns on, the edge of the
current waveform is provided by the bypass capacitor. The
remainder of the current is provided by the input capacitor.
Slower currents are provided by the upstream power supply
which fills up the input capacitor when the high side switch
is off. The current flows through the high side MOSFET and
to the output, charging the output capacitors and providing
current to the load. The current returns through a PCB
ground trace where the output capacitors are connected, the
regulator is grounded, and the input capacitors are grounded.
The second loop starts from the inductor to the output
capacitors and load, and returns through the low side
MOSFET. Current flows in the second loop when the low
side NMOSFET is on. The designer should note that there
are locations where the red line and the blue line overlap;
these areas are considered to have DC current. Areas
containing a single blue line indicate that AC currents flow
and transition very quickly. The key to power supply layout
is to focus on the connections where the AC current flows.
A good rule of thumb is that for every inch of PCB trace,
20 nH of inductance exists. When laying out a PCB,
minimizing the AC loop area reduces the noise of the circuit
and improves efficiency. A ground plane is strongly
recommended to connect the input capacitor, output
capacitor, and PGND pin of the NCP3170. Drawing the real
high power current flow lines on the recommended layout is
important so the designer can see where the currents are
flowing.
Figure 52. Recommended Signal Layout
5mg- www.onsem om
NCP3170
www.onsemi.com
25
The NCP3170 is the major source of power dissipation in
the system for which the equations above detailed the loss
mechanisms. The control portion of the IC power
dissipation is determined by the formula below:
PC+IC VIN (eq. 52)
where:
ICC = Control circuitry current draw
PC= Control power dissipation
VIN = Input voltage
Once the IC power dissipations are determined, the
designer can calculate the required thermal impedance to
maintain a specified junction temperature at the worst case
ambient temperature. The formula for calculating the
junction temperature with the package in free air is:
TJ+TA)PD RqJA (eq. 53)
where:
PD = Power dissipation of the IC
RqJA = Thermal resistance junction to ambient
of the regulator package
TA= Ambient temperature
TJ= Junction temperature
The thermal performance of the NCP3170 is strongly
affected by the PCB layout. Extra care should be taken by
users during the design process to ensure that the IC will
operate under the recommended environmental conditions.
As with any power design, proper laboratory testing should
be performed to ensure the design will dissipate the required
power under worst case operating conditions. Variables
considered during testing should include maximum ambient
temperature, minimum airflow, maximum input voltage,
maximum loading, and component variations (i.e., worst
case MOSFET RDS(on)). Several layout tips are listed below
for the best electric and thermal performance. Figure 53
illustrates a PCB layout example of the NCP3170.
1. The VSW pin is connected to the internal PFET
and NFET drains, which are a low resistance
thermal path. Connect a large copper plane to the
VSW pin to help thermal dissipation. If the PG pin
is not used in the design, it can be connected to the
VSW plane, further reducing the thermal
impedance. The designer should ensure that the
VSW thermal plane is rounded at the corners to
reduce noise.
2. The user should not use thermal relief connections
to the VIN and the PGND pins. Construct a large
plane around the PGND and VIN pins to help
thermal dissipation.
3. The input capacitor should be connected to the
VIN and PGND pins as close as possible to the IC.
4. A ground plane on the bottom and top layers of the
PBC board is preferred. If a ground plane is not
used, separate PGND from AGND and connect
them only at one point to avoid the PGND pin
noise coupling to the AGND pin.
5. Create copper planes as short as possible from the
VSW pin to the output inductor, from the output
inductor to the output capacitor, and from the load
to PGND.
6. Create a copper plane on all of the unused PCB
area and connect it to stable DC nodes such as:
VIN, GND, or VOUT.
7. Keep sensitive signal traces far away from the
VSW pins or shield them.
Figure 53. Recommend Thermal Layout
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SOIC8 NB
CASE 75107
ISSUE AK
DATE 16 FEB 2011
SEATING
PLANE
1
4
58
N
J
X 45 _
K
NOTES:
1. DIMENSIONING AND TOLERANCING PER
ANSI Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DIMENSION A AND B DO NOT INCLUDE
MOLD PROTRUSION.
4. MAXIMUM MOLD PROTRUSION 0.15 (0.006)
PER SIDE.
5. DIMENSION D DOES NOT INCLUDE DAMBAR
PROTRUSION. ALLOWABLE DAMBAR
PROTRUSION SHALL BE 0.127 (0.005) TOTAL
IN EXCESS OF THE D DIMENSION AT
MAXIMUM MATERIAL CONDITION.
6. 75101 THRU 75106 ARE OBSOLETE. NEW
STANDARD IS 75107.
A
BS
D
H
C
0.10 (0.004)
SCALE 1:1
STYLES ON PAGE 2
DIM
A
MIN MAX MIN MAX
INCHES
4.80 5.00 0.189 0.197
MILLIMETERS
B3.80 4.00 0.150 0.157
C1.35 1.75 0.053 0.069
D0.33 0.51 0.013 0.020
G1.27 BSC 0.050 BSC
H0.10 0.25 0.004 0.010
J0.19 0.25 0.007 0.010
K0.40 1.27 0.016 0.050
M0 8 0 8
N0.25 0.50 0.010 0.020
S5.80 6.20 0.228 0.244
X
Y
G
M
Y
M
0.25 (0.010)
Z
Y
M
0.25 (0.010) ZSXS
M
____
XXXXX = Specific Device Code
A = Assembly Location
L = Wafer Lot
Y = Year
W = Work Week
G= PbFree Package
GENERIC
MARKING DIAGRAM*
1
8
XXXXX
ALYWX
1
8
IC Discrete
XXXXXX
AYWW
G
1
8
1.52
0.060
7.0
0.275
0.6
0.024
1.270
0.050
4.0
0.155
ǒmm
inchesǓ
SCALE 6:1
*For additional information on our PbFree strategy and soldering
details, please download the ON Semiconductor Soldering and
Mounting Techniques Reference Manual, SOLDERRM/D.
SOLDERING FOOTPRINT*
Discrete
XXXXXX
AYWW
1
8
(PbFree)
XXXXX
ALYWX
G
1
8
IC
(PbFree)
XXXXXX = Specific Device Code
A = Assembly Location
Y = Year
WW = Work Week
G= PbFree Package
*This information is generic. Please refer to
device data sheet for actual part marking.
PbFree indicator, “G” or microdot “G”, may
or may not be present. Some products may
not follow the Generic Marking.
MECHANICAL CASE OUTLINE
PACKAGE DIMENSIONS
ON Semiconductor and are trademarks of Semiconductor Components Industries, LLC dba ON Semiconductor or its subsidiaries in the United States and/or other countries.
ON Semiconductor reserves the right to make changes without further notice to any products herein. ON Semiconductor makes no warranty, representation or guarantee regarding
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SOIC8 NB
© Semiconductor Components Industries, LLC, 2019 www.onsemi.com
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SOIC8 NB
CASE 75107
ISSUE AK
DATE 16 FEB 2011
STYLE 4:
PIN 1. ANODE
2. ANODE
3. ANODE
4. ANODE
5. ANODE
6. ANODE
7. ANODE
8. COMMON CATHODE
STYLE 1:
PIN 1. EMITTER
2. COLLECTOR
3. COLLECTOR
4. EMITTER
5. EMITTER
6. BASE
7. BASE
8. EMITTER
STYLE 2:
PIN 1. COLLECTOR, DIE, #1
2. COLLECTOR, #1
3. COLLECTOR, #2
4. COLLECTOR, #2
5. BASE, #2
6. EMITTER, #2
7. BASE, #1
8. EMITTER, #1
STYLE 3:
PIN 1. DRAIN, DIE #1
2. DRAIN, #1
3. DRAIN, #2
4. DRAIN, #2
5. GATE, #2
6. SOURCE, #2
7. GATE, #1
8. SOURCE, #1
STYLE 6:
PIN 1. SOURCE
2. DRAIN
3. DRAIN
4. SOURCE
5. SOURCE
6. GATE
7. GATE
8. SOURCE
STYLE 5:
PIN 1. DRAIN
2. DRAIN
3. DRAIN
4. DRAIN
5. GATE
6. GATE
7. SOURCE
8. SOURCE
STYLE 7:
PIN 1. INPUT
2. EXTERNAL BYPASS
3. THIRD STAGE SOURCE
4. GROUND
5. DRAIN
6. GATE 3
7. SECOND STAGE Vd
8. FIRST STAGE Vd
STYLE 8:
PIN 1. COLLECTOR, DIE #1
2. BASE, #1
3. BASE, #2
4. COLLECTOR, #2
5. COLLECTOR, #2
6. EMITTER, #2
7. EMITTER, #1
8. COLLECTOR, #1
STYLE 9:
PIN 1. EMITTER, COMMON
2. COLLECTOR, DIE #1
3. COLLECTOR, DIE #2
4. EMITTER, COMMON
5. EMITTER, COMMON
6. BASE, DIE #2
7. BASE, DIE #1
8. EMITTER, COMMON
STYLE 10:
PIN 1. GROUND
2. BIAS 1
3. OUTPUT
4. GROUND
5. GROUND
6. BIAS 2
7. INPUT
8. GROUND
STYLE 11:
PIN 1. SOURCE 1
2. GATE 1
3. SOURCE 2
4. GATE 2
5. DRAIN 2
6. DRAIN 2
7. DRAIN 1
8. DRAIN 1
STYLE 12:
PIN 1. SOURCE
2. SOURCE
3. SOURCE
4. GATE
5. DRAIN
6. DRAIN
7. DRAIN
8. DRAIN
STYLE 14:
PIN 1. NSOURCE
2. NGATE
3. PSOURCE
4. PGATE
5. PDRAIN
6. PDRAIN
7. NDRAIN
8. NDRAIN
STYLE 13:
PIN 1. N.C.
2. SOURCE
3. SOURCE
4. GATE
5. DRAIN
6. DRAIN
7. DRAIN
8. DRAIN
STYLE 15:
PIN 1. ANODE 1
2. ANODE 1
3. ANODE 1
4. ANODE 1
5. CATHODE, COMMON
6. CATHODE, COMMON
7. CATHODE, COMMON
8. CATHODE, COMMON
STYLE 16:
PIN 1. EMITTER, DIE #1
2. BASE, DIE #1
3. EMITTER, DIE #2
4. BASE, DIE #2
5. COLLECTOR, DIE #2
6. COLLECTOR, DIE #2
7. COLLECTOR, DIE #1
8. COLLECTOR, DIE #1
STYLE 17:
PIN 1. VCC
2. V2OUT
3. V1OUT
4. TXE
5. RXE
6. VEE
7. GND
8. ACC
STYLE 18:
PIN 1. ANODE
2. ANODE
3. SOURCE
4. GATE
5. DRAIN
6. DRAIN
7. CATHODE
8. CATHODE
STYLE 19:
PIN 1. SOURCE 1
2. GATE 1
3. SOURCE 2
4. GATE 2
5. DRAIN 2
6. MIRROR 2
7. DRAIN 1
8. MIRROR 1
STYLE 20:
PIN 1. SOURCE (N)
2. GATE (N)
3. SOURCE (P)
4. GATE (P)
5. DRAIN
6. DRAIN
7. DRAIN
8. DRAIN
STYLE 21:
PIN 1. CATHODE 1
2. CATHODE 2
3. CATHODE 3
4. CATHODE 4
5. CATHODE 5
6. COMMON ANODE
7. COMMON ANODE
8. CATHODE 6
STYLE 22:
PIN 1. I/O LINE 1
2. COMMON CATHODE/VCC
3. COMMON CATHODE/VCC
4. I/O LINE 3
5. COMMON ANODE/GND
6. I/O LINE 4
7. I/O LINE 5
8. COMMON ANODE/GND
STYLE 23:
PIN 1. LINE 1 IN
2. COMMON ANODE/GND
3. COMMON ANODE/GND
4. LINE 2 IN
5. LINE 2 OUT
6. COMMON ANODE/GND
7. COMMON ANODE/GND
8. LINE 1 OUT
STYLE 24:
PIN 1. BASE
2. EMITTER
3. COLLECTOR/ANODE
4. COLLECTOR/ANODE
5. CATHODE
6. CATHODE
7. COLLECTOR/ANODE
8. COLLECTOR/ANODE
STYLE 25:
PIN 1. VIN
2. N/C
3. REXT
4. GND
5. IOUT
6. IOUT
7. IOUT
8. IOUT
STYLE 26:
PIN 1. GND
2. dv/dt
3. ENABLE
4. ILIMIT
5. SOURCE
6. SOURCE
7. SOURCE
8. VCC
STYLE 27:
PIN 1. ILIMIT
2. OVLO
3. UVLO
4. INPUT+
5. SOURCE
6. SOURCE
7. SOURCE
8. DRAIN
STYLE 28:
PIN 1. SW_TO_GND
2. DASIC_OFF
3. DASIC_SW_DET
4. GND
5. V_MON
6. VBULK
7. VBULK
8. VIN
STYLE 29:
PIN 1. BASE, DIE #1
2. EMITTER, #1
3. BASE, #2
4. EMITTER, #2
5. COLLECTOR, #2
6. COLLECTOR, #2
7. COLLECTOR, #1
8. COLLECTOR, #1
STYLE 30:
PIN 1. DRAIN 1
2. DRAIN 1
3. GATE 2
4. SOURCE 2
5. SOURCE 1/DRAIN 2
6. SOURCE 1/DRAIN 2
7. SOURCE 1/DRAIN 2
8. GATE 1
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