U12 pin BIN shorts to Vss against advisement of datasheet

groupgets / kimchi-micro

An open hardware embedded SBC for the NXP i.MX8M Mini application processor

https://kimchi.groupgets.com/

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U12 pin BIN shorts to Vss against advisement of datasheet #5

Closed kekiefer closed 4 years ago

kekiefer commented 4 years ago

According to the BQ27426 datasheet:

NOTE: The BIN pin must not be shorted directly to VCC or VSS and any pullup resistor on the BIN pin must be connected only to VDD and not an external voltage rail. If an external thermistor is used for temperature input, the thermistor should be connected between this pin and VSS.

When a pack is used with the board, the BIN FET Q1 is turned on, shorting BIN to VSS

kekiefer commented 4 years ago

Rework to fix:

Future versions of the board should not include Q1, and pull BIN to VSS with 10K.