Detect USB Charge via MCP73831

Projects General Guidance
1

Hello All,
I have a little lipo charger that uses the MCP73831/2 chip. It's actually the SOT-23-5 version and here is the datasheet http://ww1.microchip.com/downloads/en/DeviceDoc/20001984g.pdf

Here is the actual product that I own

Please help me understand how I can use the A6 pin on a pro trinket to detect whether or not a usb cable is attached and charging the battery.

I was using a 1ohm-1ohm voltage divider from the 5V pin on the trinket but that seems to be getting in the way of a voltage divider that I'm using for another reading, so I had gotten rid of that and had gone with a jumper from the PROG (5) pin on the MCP73831 to the trinket A6 and had some success but now reading the data sheet again and again, I just can't figure how that worked in first place.

I see that I can use a pullup resistor from the STAT (1) pin on the MCP73831 to an input on a micro but really I don't understand how that works.

again, please help me understand how I can detect when the usb is connected.

Thank You, John

2

I looked at that little charger: I can't decipher exactly what voltages are where from the picture, but if you were to put a photoresistor right over the charge LED, you could use the varying resistance value (as a varying voltage) an an analog pin. The charge light is probably on when the USB cable is connected, but it also might go out when full charge is reached.

3

Got it. Since I had also posted my question on another forum I posted my solution over there. Check it out if you like: http://forum.allaboutcircuits.com/threads/lipo-charger-and-usb-detect.116538/

Thanks for chiming in. John