ZHCSTD4B September 2019 – October 2023 BQ75614-Q1
PRODUCTION DATA
The AUX ADC path serves as a redundancy path to the Main ADC measurement on cell voltage measurements and bus bar measurements. It also has the front end filters of a BCI filter and an AAF filter in the AUX ADC path. The AUXCELL channel and current sense channel (taken from SRP and SRN pins) in the AUX path are multiplexed (shown as the CB MUX in Figure 8-7) to share a single BCI filter and AAF filter. The CB MUX output after the front end filters is then going into one of the AUX ADC MUX and to the AUX ADC for measurement.
Because the front end filters are shared, the device has to wait for the AAF filter to settle before making any valid CB channel (AUXCELL) or SRP and SRN channel measurement. The default AAF fcutoff is 1.64 kHz which translates to additional 4.3ms settling time to complete a single CB channel measurement. The device provides 3 AAF settling time options, 4.3ms (default), 2.3ms, and 1.3ms, configured by the ADC_CONF1[AUX_SETTLE1:0] bits. The BCI filter fcutoff is 100 kHz as in the Main ADC path.
In order to achieve best measurement accuracy through the AUX ADC it is recommended to reset the ADC every time a new CB channel is locked through the AUX_CELL_SEL bits. This will ensure that the common mode error calibration routine is re-run and the measured result is compensated for common mode error.