ZHCSTD7A December 2021 – November 2023 BQ79631-Q1
PRODUCTION DATA
Pins | Components | Value | Description |
---|---|---|---|
VS2, VS3, VS10, VS11, AUX2, AUX3 | Resistor string Top | 1.32 MΩ | Resistor divider to divide down HV measurement to ADC input range. Component values are recommended ones. Other values can be chosen as long as signal is kept within ADC input range. Too large of value resistors will cause more measurement inaccuracy due to leakage at ADC pins. |
Resistor string Bot | 12.45 kΩ | ||
Optional MOSFET or Switch | 1000-V standoff | Switch to block unwanted leakage current |
Pack+ and V_Fuse+ measurements are shown in Figure 9-2.
For Pack+ and V_Fuse+ calculation, the measurements from Pack+ reading on VS3 and V_Fuse+ reading on VS11 need to be gained up by dividing gain factors Gpack and Gfuse respectively.
Aux channels can be used to provide redundant measurement to the VS channels. AUX channels could be used for independent measurements as well. When used for redundant measurement, there is an option to run diagnostics to compare AUX channel to its equally numbered VS counterpart.
Switches in the path are optional and are mainly used to minimize leakage current from the battery pack when measurement is not being performed. The BQ79631-Q1’s integrated digital low-pass filters provide the necessary filtering for the input signals.
When the optional switches are used and these switches are MOSFET switches, care must be taken to ensure the maximum signal to the ADC input is always lower than than VMOSFET_GATE – VMOSFET_VGS.