SLUUCW9 December 2023 BQ76972
The BQ76972 device integrates a voltage ADC that is multiplexed between measurements of cell voltages, an internal temperature sensor, up to nine external thermistors, and also performs measurements of the voltage at the VC16 pin, the PACK pin, the LD pin, the internal Vref used by the coulomb counter, and the VSS rail (for diagnostic purposes). The BQ76972 device supports measurement of individual differential cell voltages in a series configuration, ranging from 3-series cells to 16-series cells. Each cell voltage measurement is a differential measurement of the voltage between two adjacent cell input pins, such as VC1-VC0, VC2-VC1, and so forth. The cell voltage measurements are processed based on trim and calibration corrections, and then reported in 16-bit resolution using units of 1 mV. The raw 24-bit digital output of the ADC is also available for readout using 32-bit subcommands (the 24-bit data is contained in the lower 3 bytes of the 32-bit data, and is sign-extended to create the upper byte). The cell voltage measurements can support a recommended voltage range from –0.2 V to 5.5 V. If a cell voltage is applied that exceeds a level of 5 × VREF1 (approximately 6.06 V), the device may report a value of –6.06 V (and the cell voltage raw counts similarly would report a value of –8388608). For the best performance, it is recommended to stay at a maximum input of 5.5 V. The 16-bit cell and VC16 (stack), PACK, and LD pin voltage measurements are available by using the commands listed below.
Command | Name | Unit |
---|---|---|
0x14 and 0x15 | Cell 1 Voltage | mV |
0x16 and 0x17 | Cell 2 Voltage | mV |
0x18 and 0x19 | Cell 3 Voltage | mV |
0x1A and 0x1B | Cell 4 Voltage | mV |
0x1C and 0x1D | Cell 5 Voltage | mV |
0x1E and 0x1F | Cell 6 Voltage | mV |
0x20 and 0x21 | Cell 7 Voltage | mV |
0x22 and 0x23 | Cell 8 Voltage | mV |
0x24 and 0x25 | Cell 9 Voltage | mV |
0x26 and 0x27 | Cell 10 Voltage | mV |
0x28 and 0x29 | Cell 11 Voltage | mV |
0x2A and 0x2B | Cell 12 Voltage | mV |
0x2C and 0x2D | Cell 13 Voltage | mV |
0x2E and 0x2F | Cell 14 Voltage | mV |
0x30 and 0x31 | Cell 15 Voltage | mV |
0x32 and 0x33 | Cell 16 Voltage | mV |
0x34 and 0x35 | Stack (VC16 pin) voltage | userV |
0x36 and 0x37 | PACK pin voltage | userV |
0x38 and 0x39 | LD pin voltage | userV |