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BQ24074 - does discharge battery protection exist?

Ismail Can Dursun
Prodigy 20 points
Other Parts Discussed in Thread: BQ24075, BQ24074

Hi,

I am using BQ24074 IC for charging a single li-ion battery. The battery has no over-discharge protection. On BQ24074 datasheet, there is no clear explanation for the disconnection of battery from the load, in low battery condition. There is BQ24075 chip to do that combined with SYSOFF pin. But this IC delivers 5.5V Vout instead of 4.4V.

Does BQ24074 disconnect the battery from the output in low battery condition? (Q2 off) Do you have any chip succession that has such a functionality, similar to BQ24074?

Thanks and Best regards,

Ismail

  • 0
    TI__Guru**** 166436 points

    The bq24074 monitors for output short circuit in supplement mode by monitoring the voltage drop from BAT to OUT (i.e. the VOSC2 spec) and will turn off the FET between OUT and BAT for 60ms if too much supplement current is being drawn.  It does not proactively turn off the battery FET when the voltage drops below a threshold but will turn off the battery FET between the OUT and BAT if the battery voltage falls below the FET drive voltage of ~2.0V.  If you need additional over-discharge protection, I suggest adding a PFET between the battery and BAT pin with gate driven by an SVS like TPS3839KL30.  

    The bq24075 has SYSOFF function and is similar to bq24074.  You would still need an independent signal (like an SVS) to allow SYSOFF to internally pull high and disconnect the battery FET.

  • 0 in reply to Jeff F
    Prodigy 20 points

    Thank you  very much Jeff,

    Best regards,

    Ismail