SLUUD50 October 2024 BQ27Z758
As reported in BattSenseOutput(), the device detects short-circuits from BAT_SP or BAT_SN to PACK+ or PACK- while the low resistors or buffers are enabled. For example, BCP and BDP indicate a short-circuit on BAT_SP, whereas BCN and BDN indicate a short-circuit on BAT_SN. The detection of these short-circuits is to prevent discharging or charging the battery through alternate paths which avoid the CHG and DSG FETs. When enabling the low resistor or buffer on either BAT_SP or BAT_SN, the device waits for Protection Enable Delay to allow the voltage on the pins to settle before enabling these hardware-based protections: BCP, BDP, BCN, and BDN. Protection Enable Delay should only be increased if Transition Delay is increased above 500, which corresponds to 1000 μs. In this case, Protection Enable Delay should be increased to 4 ms to avoid BCP or BCN from being detected when transitioning from Buffer Mode.
The voltage threshold and detection time for each of these hardware-based protections is configured separately through the ProtectorCalibration() or ProtectorImage1()/ProtectorImage2() commands.
If BCP, BDP, BCN, or BDN is detected, the device switches the battery sensing output to HIZ Mode, as described in Table 6-1, to limit the current flow on BAT_SP and BAT_SN. After waiting for Protection Recovery Delay, the device configures the battery sensing output to the state based on the present conditions. During this recovery period, the battery sensing output cannot be changed from HIZ Mode.
| Class | Subclass | Name | Type | Min | Max | Default | Unit |
|---|---|---|---|---|---|---|---|
| Settings | Batt Sense | Protection Enable Delay | U1 | 0 | 255 | 3 | ms |
| Settings | Batt Sense | Protection Recovery Delay | U1 | 0 | 255 | 5 | s |