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BQ24253: BQ24253 won´t reaches maximum IN current.

Maximo Pacheco
Prodigy 40 points
Part Number: BQ24253

Support Path: /Product/Development and troubleshooting/Search the forums for my problem/

We are using a BQ24253 to power a small computer and a 3G module. We need about 1.5A so the IC was configured to 2A default. Making testings with a power variable resistor load and a lab power supply with 5V the IC is not able to sink more than 900mA. We try many settings but no way to reach higher current. Please advice if someone got to solve it. Best regards.

  • 0
    TI__Mastermind 25800 points

    Hey Maximo,

    What is your ISET resistor, ILIM resistor settings?

    Do you have a battery connected? Is it charging the battery?

    What type of supply do you have? What voltage/current limit does it have?

    Are you using the D+/D- feature? Are you changing EN1/EN2 on the charger after startup (if at all)?

    Regards,

    Joel H

  • 0 in reply to Joel Hernandez II
    Prodigy 40 points

    Dear Joel:

    Thanks for your answer. This is the configuration we are using. I used a 5A lab power supply just for testings but in the real application the BQ24253 is powered by a 5V DC-DC converter.

    We are not using the D+/D- feature.

    We was not changing the EN1 and EN2 after start up. When we do we get 1.5A that we need. So its solved. Thanks for your advice.

    Now we have another problem:

    The computer conected to the charger will lock up if its power supply get under 3.3V and the charger is not avoiding this. Even the battery discharge completely. Please advice.

    Best regards

  • 0 in reply to Maximo Pacheco
    TI__Mastermind 25800 points

    Hey Maximo,

    I'm glad to hear that your charging current was corrected. 

    In regards to your second question, is the Vsys voltage dropping below 3.3V when the battery is depleted only?

    If so, do you have an adapter/usb power supply attached to Vbus when this happens?

    If not, under what condition does the charger Vsys voltage drop?

    Regards,

    Joel H

  • 0 in reply to Joel Hernandez II
    Prodigy 40 points
    Hello Joel:
    The problem occurs when the adapter is removed and just the battery remains connected. The battery is new and fully charged.
    Best regards.
  • 0 in reply to Maximo Pacheco
    TI__Mastermind 25800 points
    Hello Maximo,

    Can you provide a waveform of the battery voltage, system voltage, adapter voltage (to show the adapter is unplugged), and system current when this drop occurs? If you cannot take a current waveform, what is your system load at this time?

    Regards,
    Joel H