Hello all,
I’ve created a buck-boost circuit to serve as a UPS for a 5V single board computer, so that the main 12V power can be removed and the 3.6V Lipo can take over without interruption.
I’m using the MP8862 and the 12V to 5V buck operation works fine. However the boost operation from 3.6 to 5V has been problematic. I had it working real well on a couple of boards but then the function was lost on both of them. Under load, the IC seems to just enter hiccup mode with the accompanying squeal.
The configuration I have is with the 4.7uH 2Amp inductor, and two 22uF capacitors on input and output, and I changed the OC resistor from 21.5K to 47K, which is what made it work when it ran fine. I’m also running the default I2C registers (5V, enabled, etc).
I’ve played with changing the inductor to a different value, adding more caps, both ceramic and electrolytic (which seem to make things worse), as well as the OC resistor back to 21.5K.
Q:
I’m just wondering if the 3.6 to 5v operation @ 400mA is possible at all, since it seems a bit border-line according to the datasheet. Could someone confirm either way, just as a sanity check?
Thanks in advance for any information!