JAJSCB2K April 2020 – July 2020 BQ77904 , BQ77905
PRODUCTION DATA
A small, low-offset analog state comparator monitors the sense-resistor voltage (SRP-SRN) to determine when the pack is in a DISCHARGE state less than a minimum threshold, VSTATE_D or a CHARGE state greater than a maximum threshold, VSTATE_C. The state comparator is used to turn the CHG FET on to prevent damage or overheating during discharge in fault states that call for having only the CHG FET off, and vice versa for the DSG FET during charging in fault states that call for having only the DSG FET off.
Table 8-4 summarizes when the state comparator is operational. The state comparator is only on during faults detected that call for only one FET driver to be turned off.
STATE COMP | CHG | DSG | MODE |
---|---|---|---|
OFF | ON | ON | Normal |
VSTATE_C Detection | ON | OFF | UV, CTRD |
VSTATE_D Detection | OFF | ON | OV, UTC, OTC, CTRC |
OFF | OFF | OFF | OCD1, OCD2, SCD, UTD, OTD, OW |