LM1770 #8: 1.8V @ 2A, 3.3V in, (Page 15)

Summary

The controller utilizes a constant on-time control scheme which eliminates the need for external compensation components, allowing the power supply designer to minimize necessary board space and reduce costs.

This design incorporates a 22µF ceramic output capacitor. Due of the lack of ESR on ceramic capacitors, a separate 50mOhm resistor is used for creating sufficient ripple at the output.

A 3.3 uH inductor value is used along with a 10 nF feedforward capacitor to help ensure stability. The 2000 ns LM1770 timing option accommodates 272 kHz operation.

Specifications

Manufacturer	Texas Instruments
Category	AC/DC and DC/DC Conversion
Sub-Category	DC/DC SMPS - Single Output
Eval Board	Board not Stocked
Topology	Step Down
Outputs and Type	1 Non-Isolated
Voltage Out: Factory Set	1.8 V
Current Out	2 A
Voltage In	3.3 V
Efficiency @ Conditions	>86%, 3.3V in, 1.8V @ 0.3 ~ 2 A
Voltage Out Range
Features	Short Circuit Protection Soft Start
Switching Frequency	272 kHz
Standby Current [Typical]
Quiescent Current [Typical]	400 µA
Component Count + Extras	10 + 0
Internal Switch	No
Design Author	Texas Instruments
Application / Target Market	Computers DVD/Blu-ray Players Point of Load (PoL) Portable Devices Set-Top Boxes Telecom USB Powered Devices White Goods
Standby Current [Maximum]
Quiescent Current [Maximum]	600 µA
Main I.C. Base Part	LM1770U
Date Created By Author
Date Added To Library	2011-03