Hi
The customer design with BQ76952, Considering the impact of current change noise on the ADC, separate CELL16 from the Vbat power supply, and share the ground at VSS and CELL0. The remaining unused pins are left floating or grounded according to the manual requirements, see the figure below.
Phenomenon 1: Single board debugging CELL16- CELL0 is all floating, VBat 12V power input, initial observation of the GW switching power supply current value is 1~2mA (switching power supply current display accuracy is poor), about 3 minutes later, the current began to fluctuate 4mA, and slowly rose to 6~7mA, and finally reached around 10mA. The switching power supply module turned off the power because the current limit was set to prohibit output (12V@20mA);
Phenomenon 2: The experimental conditions are as in Phenomenon 1. Use MCU to initialize the configuration of 76952 through IIC. The initial REG1 and REG2 are at the set voltage of about 3.3V. After about 2 minutes, the voltage begins to fluctuate, and REG1 drops to about 0.8V; When observing the Vbat power supply, the current rises to about 7~8mA, the BQ76952 IIC stops working, and the oscilloscope shows that the SCL/SDA voltage is about 0V, and SCL and SDA are forcibly pulled low; In addition, the MCU side SCL and SDA both have pull-up resistors 4.7K to 3.3V, and REG18 is around 1.8V during the entire fault process.
In addition, the VBAT power supply is disconnected, and the switching power supply displays a current of 0mA, indicating that there are no other components on the circuit board to draw power, and the current consumption is BQ76952
Thanks
Star
