Other Parts Discussed in Thread: CSD13381F4, TIDA-00792, TIDA-00449
Hi Engineer,
I would like to confirm some designs in TI’s application reports.
1. I would like to confirm that the N-MOS is feasible to be used as an external balancing MOSFET with BQ76940 (14S batteries)
(ref: http://www.ti.com/lit/df/tidrqy7/tidrqy7.pdf) Another application report also states that N-channel balance FETs can be used and may be preferred.(as discussed in http://e2e.ti.com/support/power_management/battery_management/f/1002/t/673355, and Application Report http://www.ti.com/lit/an/slua749a/slua749a.pdf).
2. If N-MOS are applicable, I would need some advice on which N-MOSFET to use with lower Leakage Current. Here are my requirements. My batteries have 4.2 V max and 2 V min, total maximum voltage 60.2 V(14S), the balancing current would be 16~20mA (I know that CSD13381F4 is one of them. But I think it will be overqualified) and the expected Leakage Current <= 100 nA.
3. I would like to know how to reduce the power dissipation in the source follower as shown below without driving too much power dissipation by internal linear regulators. My requirement would be 50 mA ~ 10 mA.
Either adding resistors, choosing the right side to put the diode pair as shown below, or choosing the suitable MOSFET (Leakage Current is still an issue.) would be appreciated.
Thanks a lot.
I look forward to your reply!
Best regards,
Matthew Cheng