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BQ25792: replacement with a battery charger featuring charge termination current near 2 mA

Newton Cardoso
Prodigy 60 points
Part Number: BQ25792
Other Parts Discussed in Thread: BQ25100, BQ24050, BQ25629

Hi all,

I am using BQ25792 battery charger in a design (1 cell) whose termination current is 2,5 mA, far below 40 mA provided by BQ25792. 

Is there a similar battery charger with such a low current termination value ?

Best wishes

  • 0
    TI__Guru*** 146905 points

    Hi Newton, 

    Measuring such low termination current is difficult for chargers with output current capabilities above 1 amps.  What feature of the BQ25792 did you need for your 1 cell application?  High input voltage?  MUX'd input? We have numerous other chargers, mostly linear, that have a better change at reaching 2.5mA accuracy.  For example, BQ25100 250mA linear charger can achieve down to 1mA termination current.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 60 points

    Hi Jeff,

    Thank you for the answer. If feasible, I'd like to have the following features: I2C controlled,  Li-ion polymer, USB BC1.2, SDP, CDP, DCP detection and power path management .

    Besr wishes,

  • 0 in reply to Newton Cardoso
    TI__Guru*** 146905 points

    HI Newton,

    So maximum charger input voltage is 5V USB?

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 60 points

    Correct, Jeff.

    Regards,

    Newton

  • 0 in reply to Newton Cardoso
    Prodigy 60 points

    Hi Jeff,

    Any tip about the suitable P/N of battery charger?

    Regards,

    Newton

  • 0 in reply to Newton Cardoso
    TI__Guru*** 146905 points

    Hi Newton,

    Unfortunately, we do not have a charger with I2C control and ITERM down to 2mA and D+/D-.  The closest options are:

    BQ24050 linear charger with D+/D- but not I2C or ITERM down to 2mA.

    BQ25629 switch mode charger with I2C and D+/D- but not ITERM down to 2mA

    BQ25100 linear charge family with ITERM down to 1mA but no D+/D- or I2C.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 60 points

    Hi Jeff

    Maybe BQ24050 could be an option. I think it has ITERM down to 2 mA. I would lose I2C. Even BQ25629 with 5 mA of ITERM sounds better than the 40 mA of BQ25792.

    Looking at BQ24050 datasheet, it seemed to me that if I use 40 mA as current of fast charge (ISET), the termination current could be 2 mA.(5% of ISET)

    The values of 40 mA for ISET and termination current corresponding to 5% of ISET were found on the excerpts below:

     As section 7.5.1 PRE_TERM of BQ24050 datasheet states that "The termination can be set between 5 and 50% of the programmed output current level set by ISET" ., and Table 5-1. Pin Functions says that ISET " Programs the Fast-charge current setting. External resistor from ISET to VSS defines fast charge current value. Range is 52.3k (10 mA) to 540 Ω (1 A)".

    Please would you kindly check if my reasoning is valid?

    Regards,

    Newton

  • 0 in reply to Newton Cardoso
    TI__Guru*** 146905 points

    Hi Newton,

    I think you are correct.  I did the computation below but double check me.

    Please note that D+/D- only detects SDP or not SDP.  If not SDP, the input current is limited per ISET2 pin setting.

    Regards,

    Jeff