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bq24090 TTDM

Marc Palmano
Prodigy 50 points
Other Parts Discussed in Thread: BQ24090, BQ27510-G2, BQ27510

I am using a bq24090 to charge a battery and power the system.

Currently I have TS floating, with the ability to pull it down via

-  bq27510-g2 BAT_GD output (as required for obtaining the OSV measurment for the fuel gauge)
- a host processor via open drain mosfet

The system load is typically light 40mA but can peak at over 500mA.

Charging current is set at 100mA normal with ability for the host to pull ISET2 to gnd boosting it to 500mA.

Temeperature monitoring is being done using the bq27510-g2's internal sensor and as the fule gauge is talking to the host charge control can be transferred to the fule gauge/host.


My question is should I be using TTDM mode or should I connect a 10k resistor from TS to gnd and use the normal mode (with no temp sensing)?

Thank you

  • 0
    TI__Guru**** 166576 points

    In TTDM, the 10 hour safety timer is held in reset and charge termination is disabled.  Precharge timer still functions.  /CHG still functions normally but battery will continue to charge until current reaches 0 A.  I recommend that you implement a safety timer but this can be done with a processor.  The gauge or /CHG will provides information about charge termination.

  • 0 in reply to Jeff F
    Prodigy 50 points

    Thanks Jeff,

    /CHG  is fed back to the host plus we have the bq27510 fuel gauge so we can implement the safety timer as you recommended.

  • 0 in reply to Jeff F
    Prodigy 40 points

    hai!

           This is vanaja,I am using BQ24090 (Battery Charger) and  am using circuit as specified in datasheet

    1. ISET Resistance is 1k  for 540mA,

    2. PRETERM resistance is 2K,

    3. ISET2 is connected to VCC,

    4. Led's are connected to PG and CHG pins,

    5. my battery not having NTC, so TS pin left floating

    I have a doubt like when PG and CHG led's are ON and OFF,how to know the current termination or Battery full please explain about this clearly.

    Thanks.

  • 0 in reply to Gowri Shankar V
    TI__Expert 7730 points

    Answered in the other duplicated post.