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Isolated buck/boost converter?

Isolated buck/boost converter?

Isolated buck/boost converter?

Does anyone have a suggestion for a controller IC for an isolated buck/boost converter? External switch OK.

Basic specs:
Input - 5VDC to 16VDC
Output 9VDC @ 2 amp


RE: Isolated buck/boost converter?

Yes, I'm looking at the LM2587S-ADJ, but would be interested in other opinions - there are a gazillion controllers available form all the semi vendors these days.


RE: Isolated buck/boost converter?

There are many good ones.  It's hard to justify not using a fully designed implementation out of National's design workbench area.

Click a button and you can have the entire kitted system sent to you with a circuit board.

Perhaps they don't have isolation.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Isolated buck/boost converter?

Can do 2 stages:
1st stage 1:2 transformer connected to H-bridge (with 4 power N-FETs) producing double ouput voltage. Can easy run with 500kHz, open loop (add few hundred mV for diodes drop).
Output will be 10 to 32V.
(check IR chips with oscilator inside and bootstrap for "all N-FETs")

Then Buck down to 9V with old and robust Unitrode chip UC2573 and external P-FET (say 50V, 8A).
I did 10000000 Bucks with this chip - never problem.

LM2587 - need to do isolated feedback (opto or something like this...). Plus - think what to do with wide input range. (I won't use this National chip)


RE: Isolated buck/boost converter?

A simple isolated flyback supply should be up to the job.

It just requires a standard straight out of the application notes circuit, and suitably designed magnetics.

RE: Isolated buck/boost converter?

Thanks for all the responses. I ended up using the National LM2588-ADJ. Proto9 boards are being made as we speak.

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