| Condition | CHG FET | DSG FET | Pack output | |-----------|---------|---------|--------------| | Normal operation | ON | ON | Enabled | | Overvoltage | OFF | ON | Disabled (can’t charge) | | Undervoltage | OFF | OFF (or ON if precharge) | Disabled | | Overcurrent (discharge) | OFF | OFF | Disabled | | Overtemperature | OFF | OFF | Disabled |
| Command (hex) | Name | Description | |---------------|---------------|---------------------------------| | 0x02 | Temperature | Pack temperature (0.1°K) | | 0x04 | Voltage | Pack voltage (mV) | | 0x06 | Current | Pack current (mA) | | 0x08 | RemainingCapacity | mAh | | 0x0C | RelativeStateOfCharge | 0–100% | | 0x10 | CycleCount | Number of discharge cycles | | 0x16 | CellVoltage1–4 | Per-cell voltages (mV) | | 0x44 | ManufacturerAccess | Access to data flash, control functions |
Technicians communicate with the chip via its SMBus pins (Data, Clock, and Ground). This requires an I2C/SMBus adapter such as: bq40370
) and functions as a heatsink to dissipate thermal build-up caused by high-accuracy analog operations.
The BQ40370 is a highly integrated and accurate battery management IC suitable for a wide range of portable and wearable applications. Its low power consumption, high accuracy, and configurability make it an ideal choice for designers looking to optimize battery performance and extend battery life. | Condition | CHG FET | DSG FET
Monitors internal cell resistance over time.
Developing with the BQ40370 requires a specific set of tools. The ecosystem is designed for precision configuration and testing. The ecosystem is designed for precision configuration and
For new product development in 2024-2025, do not use the bq40370 . TI lists it as "NRND." Use the BQ40Z50-R2 or BQ40Z80. However, if you are maintaining legacy medical or industrial equipment, you must stick with the bq40370 for drop-in compatibility.
: The core algorithm determines remaining battery capacity based on modeling the battery’s voltage discharge curve under varying loads and temperatures. It uses pre-programmed voltage trip points (EDV0, EDV1, EDV2) to dynamically adjust when the battery is nearing zero capacity.
: The bq40370 is programmable; firmware updates or resets are often necessary when "re-packing" battery cells to clear error flags (like "Permanent Failure") that prevent the battery from charging. Common Use Cases Battery Repair