Hello，
Our device is powered by two external power supplies, which are converted to 5V voltage by a selection circuit and then MPM3620A converted to 5V voltage by using a selection circuit to power the MP2723. During operation, when both external power sources are accidentally powered off, the battery may not be discharged through the MP2723. After testing, the battery voltage is 4.1V, and the VSYS voltage is 0.365V. I also tested some voltage:BATT 4.081V,VREF3.615V,DISC 3.583V.When I connect any external power supply, this abnormal state is removed. What could be the reason for this?
schematic is as bellow
Hi
when i connect one of the two external source,the chip work normally.batt is 4.162V(we set the battery voltage to 4.1V),VREF is 3.673V,VSYS is 4.215V,DISC is 3.640V.
This abnormal phenomenon does not happen every time there is a power failure. When an abnormality occurs, it disappears once the external power supply is connected
Hello,
Probably there might be some issue with the selection circuit as the input of MP2723 as you mentioned the abnormality disappears if you connect one of the external power supply. I would recommend checking the selection circuit first.
Hello
I don’t quite agree with what you’re saying. The following figure is my power topology, I said that this problem will occur when all AB is accidentally disconnected, which is equivalent to the MP2723 input power disconnection after the battery can not be discharged. I don’t think this has anything to do with the power selection circuit. What do you think?
Thank you for sharing the block diagram. What’s the DISC pin voltage when this abnormal state occurs? Can you also share the waveforms of DISC pin and Vsys pin when inputs A and B are removed or turned off?
