[8] Charger: CHARGER gets stuck for certain types of PCM

This anomaly applies to Revision 2, build codes CAAA-E00, CAAA-F00, CAAB-F00, QDAA-F00, QDAB-F00.

It was inherited from the previous IC revision Revision 1.

Symptoms

Battery stops charging, and CHARGER gets stuck in error state.

Conditions

VBAT voltage drops from above V_TRICKLEFAST to below V_TRICKLEFAST during charging.

Some battery Protection Circuit Modules (PCM) add a diode junction between the external battery terminals and the lithium cell when the overdischarge protection is active. This diode adds a voltage to the battery terminals during charging. When the protection is released, the diode junction is bypassed and the VBAT voltage drops.

Consequences

Charging stops when overdischarge protection is released, and the charging cannot be restarted.

Workaround

Use a battery with a PCM that does not cause this drop when overdischarge protection is released. Alternatively, use a battery with a PCM that drops to a voltage that is higher than V_TRICKLEFAST or drops from a voltage that is lower than V_TRICKLEFAST.