BQ25690: support Super Cap issue

Tommy Tzeng

Part Number: BQ25690

Hi Tema,

our customer is planning to use the BQ25690 for a superCap application, and we have the following question:

1. 6S1P 100F, voltage ration rating 2.3V, so total voltage rating is 13.8V
2. System working voltage, 13.8~8V
3. Input 5V/900mA, or 12V(nice to have)
So we need to put VREG to be very close to 13.8V, no less than 13.4V. Is it possible to using HW setting only for BQ25690? Or need FW setting, how without let cap to be over voltage?

4 months ago

0 Jeff F 4 months ago

TI__Guru**** 180716 points

Hi Tommy,

Yes, you can use HW setting to set VREG. But in your case, there is not a combination of CELL count and VCHG that gives 13.4-13.8V. I recommend using I2C through FW to set the exact value you need.

Regards,

Jeff

0 Tommy Tzeng 4 months ago in reply to Jeff F

Mastermind 6410 points

Hi Jeff,

if the customer set the VCHG pin to 27.4kohm and CELL pin to 8.25k ohm via H/W, the total chargeing voltage will be 13.05v, keeping it below 13.8v as a priority, the VCHG nad ICHG can then be further adjusted via the i2c interface. to prevent the superCap from being damag. right?

+1 Jeff F 4 months ago in reply to Tommy Tzeng

TI__Guru**** 180716 points

Hi Tommy,

Yes.

Regards,

Jeff

Power management

Power management forum

BQ25690: support Super Cap issue