Other Parts Discussed in Thread: BQ2085,
Tool/software:
Hello TI team,
we are using the BQ2085 together with the BQ29311 in a 3S1P application. Our customer has now complained that 7 batteries are discharging too quickly.
We have analyzed the 7 batteries and found out that the PCB draws more current than usual. The normal current consumption on a OK circuit board in active mode is 500µA, the defective curcuit boards consume 1.5mA. This higher current is only drawn in active mode, in shutdown mode the current consumption of the OK circuit board and the defective circuit boards are the same (~0). Beside the higher current consumption, the defective boards seem to operate normally.
We have identified a slightly higher temperature on the BQ29311 of the defective circuit boards in comparison to the OK circuit board. We then have swapped the BQ29311 of the OK circuit board and a defective curcuit board and the higher current consumption moved along. So the before OK circuit board now draws ~1.5mA and the before defective circuit board now draws 500µA. We have done that for all 7 circuit boards and the result was always the same. So it seems like the BQ29311 is responsible for the higher current consumption on all 7 defective circuit boards.
We gave 3 OK circuit boards and the 7 defective circuit boards to a service provider who did an analog signature analysis for the individual pins of the BQ29311. On all 7 defective circuit boards he found a deviation on pin 17 (XALERT) of the BQ29311:
The green curve shows pin 17 of a OK circuit board and the red curve shows pin 17 of a defective board.
Now my questions:
- Do you have any idea why the 7 BQ29311s drawing more current than usual? Are you aware of similar cases?
- Do you have an explanation for the curve behavior at pin 17 (XALERT)?
- Could this be reason for the 3x higher current consumption?
Many thanks in advance for your response.
