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bq78350-R1 Charge Protection

Sheldon Rubin
Intellectual 540 points

Overcurrent in Charge Protection

OCC trips when Current() continuous ≥ OCC:Threshold for OCC:Delay duration

OCC recovery occurs when:

  1. [SafetyStatus()[OCC] = 1 and
  2. Current() continuous ≤ OCC:Recovery Threshold for OCC:Recovery Delay time

The default value for OCC:Threshold is 6000mA, meaning OCC will trip when charge current exceeds 6A

The default value for OCC:Recovery Threshold is -200mA, meaning OCC will recover when discharge current exceeds 200mA.

Here are my questions:

  1. Based on default values, why is a discharge current required to recover from an overcurrent in charge? Wouldn’t that prevent subsequent charging unless a load is connected to the battery or the charger at last partially discharges the battery? For our application, the battery will be removed from the system for charging and will have no load connected at that time
  2. The table in Section 3.4 of the TRD states that when tripped “charging is not allowed”. Does this mean that the CHG FET is turned off until the recovery criteria are satisfied?
  3. In the same table, the description of Recovery Threshold and Recovery Delay mention “Overcurrent in Charge 1 and 2 …”. What is Overcurrent in Charge 2?

  • 0
    TI__Guru 73830 points
    1. We recommend using a discharge current for the Recover threshold to prevent the protection feature from cycling on and off until the over current condition is removed. You can set the threshold to a charge current, if desired.

    2. Correct

    3. This is an error in the TRM. There is only one OCC in this device. Some devices have two OCC set thresholds and recovery thresholds.