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BQ25798: Connecting Two Charger IC Solution

parth kalaria
Prodigy 80 points
Part Number: BQ25798
Other Parts Discussed in Thread: LM66200

Tool/software:

Hello,

We are planning to connect two charger IC as per the attached block diagram.

Connection Summary: 

1. Common input for both charger ICs.

2. Different I2C connected from Host PC.

3. Different Battery is connected to both charger ICs.

4. Only VBUS input considered for the Charger IC input. ACDRV1 and ACDRV2 connected to ground.

We have below queries for the output Voltage connection:

1. Both charger ICs outputs are shared and supplied to the system load. Can we therefore share both of the charger IC's outputs or it will result in an electrical problem?

2. Do we need to add reverse current protection or an ideal diode to both charger outputs in case one of them fails? If yes, could you please suggest part# of ideal diode?

3. Does the testing reveal any electrical challenges in the solution?

  • 0
    TI__Guru**** 166576 points

    HI Parth,

    Regarding 1 and 2, you will need an ideal diode to prevent higher voltage battery from potentially back driving the lower voltage battery.  LM66200 might work.

    Regarding 3, with ideal diode, I see no issue.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 80 points

    Hello Jeff,

    Thank you for the feedback.

    The suggested part# is for selecting either one supply at a time. But we require equal load sharing from both the input supply. Also, our system voltage is 7.4V. So could you please suggest the part# accordingly.

    Can the LM73100 part number be used for the same purpose?

    Regards,

    Parth

  • 0 in reply to parth kalaria
    TI__Expert 6255 points

    Hi Parth,

    Driving 1 at a time would be the best option. Since the two batteries are separate, they might be at different voltages. If the batteries are at different voltages, then the systems would be at different voltages. This would not allow for load sharing.

    Using the LM73100, would you have 2 of them connected with their inputs to each respective battery charger and a shared output? This would have the same effect as the LM66200 where only one is active at a time.

    Best,
    Michael