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LiPo not charging using MCP73831

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joeyjoejoe:
Can someone double-check for anything obvious I've missed?

5V USB is VDD.

I am pulling up the STAT as per the datasheet, and it's always reading HIGH. It should read LOW when charging (either fast or slow charge). (Page 13)





Datasheet : https://cdn.sparkfun.com/assets/learn_tutorials/6/9/5/MCP738312.pdf

Mr.B:
I only have two observations from the datasheet.
You would need to confirm if your project has taken these into account:
Page 11.
3.1) A supply voltage of [VREG (typical) + 0.3V] to 6V is recommended. Bypass to VSS with a minimum of 4.7 µF (Your schematic does not appear to have this cap.)
3.6) An internal electrical connection exists between the Exposed Thermal Pad (EP) and the VSS pin. They must be connected to the same potential on the Printed Circuit Board (PCB) (Your schematic does not appear to show the connection of EP to Vss)

joeyjoejoe:
You are correct, I did miss a bypass cap on VDD. I will try to bodge a 4.7uF on there.

As for the pad, that applies only to the DFN package, I am using the SOT package.

joeyjoejoe:
Bodge complete - no change in behavior unfortunately.

aiq25:
On your schematic it looks like STAT is pulled up to a 3.3V rail but on the app note it shows as connected to the input voltage (I assume in your case VBUS). Did you tie STAT to VBUS or is this schematic part of a larger circuit that has a 3.3V rail? Not sure if this matters but thought I would point it out.

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