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BQ24130: Inrush current issue when start up for super cap.

Michael Jeong1
Expert 2600 points
Part Number: BQ24130

Hi,

Our customer is using BQ24130 for charging super capacitor.

They have a issue.

Inrush current (2A) has happened for about 500ms when start up charger.

There is no Vin voltage spike at that time.

Only for issue when connect super cap. to charger IC. 

For resolve this issue, Can I get your advice and reference schematic?

Below is customer schematic.

Best Regards,

  • 0
    TI__Genius 10385 points

    Michael,

    The schematic looks as expected. A 5-ohm resistor instead of a 10-ohm resistor is recommended for AVCC when  using a 5V source.

    Could you explain the purpose of the added input stage circuitry? Are you seeing this issue if you bypass the circuitry?

    Thanks,

    Ricardo

  • 0 in reply to Ricardo
    Expert 2600 points

    Hi Ricardo,

    Thanks for your reply.

    Added input stage circuitry is for control charger on/off by MCU.

    Yes, we can see this issue when we bypass the circuitry.

    Also, we can see issue between charger output and super cap.

    Don't you have any idea and solution?

    This issue is very critical to our customer.

    Pls, help us and give me a good guide. 

    Best Regards,

    Michael

  • 0 in reply to Michael Jeong1
    TI__Genius 10385 points

    Michael,

    Is this inrush occurring at the input of the charger or the output of the charger?

    Thanks,

    Ricardo

  • 0 in reply to Ricardo
    Expert 2600 points

    Hi Ricardo,

    Inrush has occurred at output of the charger.

    We set fast charge current 610mA.

    I can't understand why this inrush has occurred at output of the charger when start up charging.

    We don't have a enough time.

    Could you please give me guide and explain?

    Best Regards,

    Michael

  • 0 in reply to Michael Jeong1
    TI__Genius 10385 points

    Michael,

    I am not sure what is happening. If you remove the capacitor and short to S-CAP_PWR to GND what current do you see? If you replace the super capacitor with with a sourcemeter or CV load and sweep the voltage are you able to see expected performance?

    Thanks,

    Ricardo