Other Parts Discussed in Thread: BQ77PL900, BQ76940, BQ77904
In our recent project we use bq7791506 . We are experienced on BMS control IC's of Texas Instruments.
Previously we used different ICs for different projects such as bq77PL900, bq77904, bq76940.
In our recent project bq7791506 holds every specification given in datasheet (SLUSCU01) except current state comporator.
Technical details on this situation:
- Rsense= 0,25mOhm
-There is no problem about current sense and current protection cases. (SRP-SRN connections are OK)
- During charge:
i. battery pack goes into UVP when any cell voltage is under 2,5V (it is OK)
ii. When charger is started charge Dicharge FETs are not turned ON. Current flow through body diode of discharge FETs.
This situation does not change with charge current. we applied charge currents 2A, 5A, 10A, 15A, 20A, 25A, 60A.
According to datasheet Vstate-c=1,875mV that means current above 7,5A should turn on discharge mosfet.
iii. Discharge MOSFET is turned on only cell voltages reach 2,9V and above.
-During discharge:
i.While 100A dishcarge is drawn from pack charge FETS are turned off because of OTC temperature. this causes more power dissipation on FETs and because of increasing temperature BMS turns off the discharge.
- In both situaition (charge and discharge) our FETs or PCB does not fail. It goes in protection and then recovery ( 2,9V for UVD and cooling for over temperature)
-But obviously Current State Comparator does not work in both cases. This is a clear contradiction with datasheet.
We will be glad if you can inform us about this situaiton.
Best regards
Serdar Özbek