Switch mode supply question for OnSemi NCV5171 IC

Status
Not open for further replies.

Joe Voytovich

Newbie level 6
Joined
Feb 24, 2014
Messages
14
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Visit site
Activity points
170
I'm re-doing a power supply board at work that takes in 2-35V from a generator and puts out 10V. Previous version used a TI chip, but that had a max input of 6V, so we had used a linear regulator pre-stage. This got HOT at higher inputs, so on to a new design.

I'm now using an On Semi NCV5171 chip. I put this together Friday and didn't get good results. The voltage spiked up briefly to about 3V, then drifted down. After tying a 100 ohm load to the output, I noticed a little whiff of smoke but don't really know where it came from. The spec says the IC is protected from over-temp (at 180C) and over-current.

Anyway, my question is on the circuit in the spec on the boost-buck mode - the SEPIC design. The 2 inductors shown in the circuit have dots on them - one open and one filled. This would indicate that they are windings on a transformer, but the spec also mentioned inductorS used - with an S, meaning more than one, and the circuit shows 22uH on each.

If this is the case, I will need to do some more tuning on the circuit with the soft start and compensation. UGH!!!

Anyone have any experience with SEPIC-type circuits, or this chip in particular??

Thanks.

 

Status
Not open for further replies.

Similar threads

Cookies are required to use this site. You must accept them to continue using the site. Learn more…