Design contains obsolete parts

LM1770 #1: 3.3V @ 2A, 5V in, (Page 1)

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 higher frequency design enables the use of a small valued inductor (1 µH) and a 68µF OSCON output capacitor, reducing component size. A stable design is possible without the use of a feed-forward capacitor, further reducing necessary board space.

For the PFET and the NFET, the SI3867DV and the SI3460DV are chosen due to their desirable RDS(on) specifications, current handling capabilities and small footprints. The 1000 ns LM1770 timing option is used to implement the 1 MHz frequency.

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	3.3 V
Current Out	2 A
Voltage In	5 V
Efficiency @ Conditions	>87%, 5V in, 3.3V @ 0.5 ~ 3 A
Voltage Out Range
Features	Short Circuit Protection Soft Start
Switching Frequency	1 MHz
Standby Current [Typical]
Quiescent Current [Typical]	400 µA
Component Count + Extras	9 + 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	LM1770T
Date Created By Author
Date Added To Library	2011-03