SLUSE48B May 2021 – November 2023 BQ79652-Q1 , BQ79654-Q1 , BQ79656-Q1
PRODUCTION DATA
The device can detect an open wire connection on the VC and CB pins. A current sink is connected to each VC and CB pin, except VC0 and CB0 pins which are connected with a current source.
When the current sink (or current source) is enabled and if there is an open wire connection, the external differential capacitor will be depleted and the cell voltage measurement will drop to an abnormal level over time. Similar detection concept applies to the VC0 and CB0 pins with a current source. If there is an open wire connection, the VC0 or CB0 will be pulled up by the current source, resulting in a reduced cell voltage measurement over time.
When the diagnostic comparison is enabled, the device will compare the cell voltage measurement from Main ADC (for VC pins open wire detection) against a host-programmed threshold; or comparing the AUX CELL measurement from the AUX ADC (for CB pins open wire detection) against a host-programmed threshold.
If MCU lock to a single CB channel though [AUX_CELL_SEL] before starting the CB open wire check. The device will report the AUXCELL measurement used for the check comparison. The value is reported in DIAG_AUX_HI/LO registers. Since there is no single channel lock mechanism in Main ADC, VC channel measurement used for VC open wire will not be reported in DIAG_MAIN_HI/LO registers.
Before starting the open wire comparison, host ensures:
To start the open wire comparison:
Host checks the FAULT_COMP_VCOW1/2 or FAULT_COMP_CBOW1/2 registers for the comparison result.