LMR62421 as SEPIC

ee06091

Other Parts Discussed in Thread: LMR62421, TPS62162, TPS63061, TPS62120, TPS62125

I have an application that needs 3.3V and 5V from 4 Alkaline AA batteries. From what I read the AA voltage will vary from 1.5V to 1.1V so I'll get 6V to 4.4V. I was thinking to use one TPS62162 to convert from 6V-4.4V to 3.3V and then one LMR62421 to convert the 3.3V to 5V. I didn't know about SEPIC converter.

Now I'm thinking to use LMR62421 as SEPIC so can convert the 6V-4.4V to 5V and then use a LDO for 5V, do you think it is ok?

How can use the webench design the test the SEPIC design? On the datasheet the SEPIC converter use the WSON package but it only have one more pin the AGND, can it be made with the TSSOP package?

Thank you

over 11 years ago

0 Chris Glaser over 11 years ago

TI__Guru**** 150820 points

A SEPIC is rather complicated and not a needed topology for these low voltage applications. A buck-boost converter is simpler and more integrated resulting in a much smaller solution size. The TPS63061 is a great device here.

The TPS62162 is also a good device. The TPS62120 and TPS62125 would be lower current devices that might be better suited for your current needs.

If you want support on an LMR device, please post in the simple switcher forum.