SLUSF21 Data sheet

SLUSF21 june 2023 BQ79616

PRODUCTION DATA

Package Options

Mechanical Data (Package|Pins)

PAP|64
- MPQF071C

Thermal pad, mechanical data (Package|Pins)

PAP|64
- PPTD012N

Orderable Information

8.3.3.1.3 Step 3a: Balancing Thermal Management

With passive balancing, heat is generated through the internal CBFETs and the external balancing resistors. This creates two hotspots on the PCB, the device, and the balancing resistors area. The device is designed to support up to 240 mA at 75°C ambient. Higher balancing current can be supported with lower ambient temperature.

The device provides two thermal management functions to avoid overheating the die as well as managing the PCB temperature. Both functions monitor temperature, either die temperature or thermistor temperature, to automatically pause balancing if temperature exceeds a pause threshold. When temperature falls below a recovery threshold, balancing resumes automatically. In the cell balancing pause state, all balancing timers and balancing settings are “frozen”, balancing will resume with the same configuration when the device is out of the pause state.

CB TWARN Balancing Pause: There are die temperature sensors built near the internal CBFETs. When [BAL_GO] = 1 is sent, these temperature sensors are enabled. If any of the sensors detect a die temperature > than the T_{CB_TWARN} threshold (105°C nominal), balancing on all channels is paused. The device sets the BAL_STAT[CB_INPAUSE] = 1 and BAL_STAT[OT_PAUSE_DET] = 1. When all sensors detect die temperature < (T_{CB_TWARN} – T_{CB_HYS}), cell balancing will resume on the balancing enabled channels.
Thermistor OTCB Balancing Pause: To manage thermal increases due to external balancing resistors, the device has an option to pause cell balancing on all channels if any of the active thermistors connected to GPIOs detects a temperature greater than a threshold set by OTCB_THRESH[OTCB_THR3:0]. Once a OTCB detection is triggered, the BAL_STAT[CB_INPAUSE] = 1 and BAL_STAT[OT_PAUSE_DET] = 1. The balancing on all enabled channels will resume once all active thermistors detect a temperature less than a recovery threshold set by (OTCB_THRESH[OTCB_THR3:0] + OTCB_THRESH[COOLOFF2:0]). The OTCB detection is performed through the integrated OT protector. The protector must be turned on and running in round robin mode before cell balancing starts. See Section 8.3.4 for the protector control details. To use the OTCB function, MCU follows the setup sequence state below:
- Before enabling OT protector:
  - GPIO used for this function will be configured to ADC and OTUT inputs.
  - [OTCB_THR3:0] and [COOLOFF2:0] are configured.
- Enable the OT protector in round robin mode.
- Set [OTCB_EN] and [BAL_GO] to 1.
Failure to do so may result in no OTCB pausing action or pausing at the wrong temperature. If a different OTCB or COOLOFF threshold is needed, MCU configures the new threshold values and then re-starts the OT protector to latch in the new setting. It is not required to resend the [BAL_GO] = 1.

Figure 8-17 Cell Balancing Pause and Resume by OTCB Detection