TI BQ76925RGET

The bq76925 is a host-controlled analog front-end (AFE) designed as part of a complete battery pack monitoring, balancing, and protection system for 3, 4, 5, or 6 series-connected lithium-ion and lithium-polymer cells. The bq76925 device enables a host controller to easily monitor individual cell voltages, pack current, and temperature. The host can use this information to identify unsafe or fault conditions such as overvoltage, undervoltage, overtemperature, overcurrent, cell imbalance, state of charge, and state of health. Cell input voltages are level-shifted, multiplexed, and scaled for output to the host ADC for measurement. A dedicated pin provides a calibrated, low-drift reference voltage to enable accurate measurements. The voltage across an external sense resistor is amplified and output to the host ADC for charge and discharge current measurement. Two gain settings allow the device to be used with a variety of sense resistor values to accommodate a wide range of pack currents. To enable temperature measurement by the host, the AFE provides a dedicated output pin for biasing an external thermistor network. This output can be switched on/off under host control to minimize power consumption. The bq76925 device includes a comparator with dynamically selectable thresholds for current monitoring. The comparator result is driven through an open-drain output to alert the host when a threshold is exceeded. This feature can be used to wake the host upon load connection or to report potential fault conditions to the host. The bq76925 device integrates cell-balancing FETs that are fully controlled by the host. Balancing current is set via external resistors, with a maximum of 50mA. These same FETs can be used in conjunction with cell voltage measurements to detect open-circuit conditions on cell sense lines. The host communicates with the AFE via I²C interface. Optional packet CRC is available to ensure communication robustness. The device can be placed into a low-current sleep mode via I²C and woken by pulling up the ALERT pin.

• Analog interface for host cell voltage measurement
• Cell input multiplexer, level translator, and scaler
• Calibrated 1.5V/3.0V low-drift reference voltage for accurate ADC conversion
• Analog interface for host current measurement
• Variable-gain current sense amplifier, compatible with 1mΩ sense resistor
• Switchable thermistor bias output for host temperature measurement
• Overcurrent comparator with dynamically adjustable threshold, reporting potential overcurrent faults to host
• Wake host upon load connection
• Integrated cell balancing FET
• Individual host-controlled cell balancing current of 50mA per cell
• Cell sense wire open-circuit detection support
• Integrated 3.3V regulator for powering microcontroller or LED
• I²C interface for host communication
• Optional packet CRC for robust communication
• Supply voltage range: 4.2V to 26.4V
• Low power consumption: 40μA typical in normal mode, 1.5μA maximum in sleep mode
• Available in 20-pin HTSSOP or 24-pin VQFN package

• Lithium-ion battery pack primary protection
• Cordless power tools
• Light electric vehicles (e-bikes and e-scooters, etc.)
• Uninterruptible Power Supply (UPS) systems
• Medical devices
• Portable test equipment