We are using BQ76952 in a 16S configuration with external balancing N-MOSFETs. As recommended by TI in Cell Balancing with the BQ769x2 section 2.2 External Cell-Balancing Circuit Design Using N-Channel FETs. Here we have observed that during normal operation(voltage and temperature measurement no balancing) with ambient of 25 °C the AFE die temperature reports to about 45 °C. in this condition when balancing for alternate cells is turned ON (8 cells in total) the temperature reported by AFE goes to about 60 °C. Our product is designed to work at 55 °C ambient temperature, which means we would cross the max operating temperature of 85 °C when working at our max ambient temperature and start the balancing operation
1. Is this behavior expected? if no then what can we do to reduce this rise in temperature?
We understand the following:
- We could reduce the number of channels balancing at a time. Though we do not want to take this approach as it affects our balancing time on the system level.
- We can program the temperature cutoff inside the AFE as mentioned in the datasheet. However, this would mean we can only perform the balancing operation at ambient of 25 °C
Circuit Diagram:
Thermal image of the Board: ( 60 degree die temperature reported by AFE)(alternate cells being balanced)
