Other Parts Discussed in Thread: TPS2121
Hello,
I have been looking for solutions to implement a usb C 5V power input source simultaneously with a PV panel rated at 6.3 V VMPP 7.4V Voc and 3A Isc. The reason for this is to be able to charge my battery in periods of low solar exposure. I noticed there were a few issues stopping me from doing this.
1. I was not sure how to implement the USB source safely so that I do not feed voltage back into my PV panel (other than of course using a schottky diode).
2. Keep the programmed MPPSET voltage divider constant without having the need to accommodate for the change in voltage source (i.e be able to efficiently charge the battery from the usb without needing to worry about my MPPSET voltage being below 1.2V)
Some solutions suggested were: boosting the incoming USB voltage to one that is similar to my solar panel's VMPP voltage or using a power MUX (such as the TPS2121) to alternate between solar and usb input but I fear each of the suggested solutions would still provide compatibility issues down the line with my design since the battery is required to charge quickly and efficiently.
I have provided a PDF file of my schematic below, the pins I am concerned about are the VCC and MPPSET pins.
Any help on how to implement this into my design would be greatly appreciated.
Thank you
