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bq24295 PMID pin current limit

Sreekanth Anegunda
Intellectual 975 points
Other Parts Discussed in Thread: BQ24295

Hello,

I have selected BQ24295 for charging the battery. I have few questions.

1. What is the maximum current can be drawn from the PMID pin. The data sheet says IOTG_LSOCP LSFET cycle by cycle current limit 5A. This means that i can draw maximum of 5A from PMID pin.

2. Can we limit the current drawn from the PMID pin?

3. If I am drawing 2.5A from PMID pin and if I connect a external charger of 1A. What will be the behaviour of the IC.

Thanks & Regards,

Sreekanth

  • 0
    TI__Genius 10240 points

    Please find my answer below:

    1. The current drawn from PMID can be very high until the Q4 or battery over current protection (OCP) is reached. The IOTG_LSOCP LSFET current limit is a cycle-by-cycle limit and PMID current is an average current. If the cycle-by-cycle current limit is reached, the OTG voltage will drop and the regulation is lost, but you still can draw higher current from PMID.

    2. No. because there is a path Battery -> Q4 -> Q2 body diode with no current regulation control, similar to a boost converter.

    3. PMID is a voltage source and the external charger could be equivalent to a voltage source too. This is similar to parallel two voltage sources and not recommended

  • 0 in reply to ezhao
    Intellectual 975 points
    Hello Ezhao,

    Thanks for the response.

    1. Is it possible to draw a max of 2.5A of current from the PMID pin? I want to use the IC for charging a Li-Ion battery of 3.7V 25Ah. So if the battery voltage drops to 3V, will I be able to draw 2.5A current?

    2. I have observed that when the charger IC is connected to PC the output current will become zero and if I connect the charger IC to the external supply the IC I am still able to draw the current at the output.

    BR,
    Sreekanth