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TPS2069D: TPS2069D

John Ruby
Prodigy 20 points
Part Number: TPS2069D

Hi, I am contemplating using the TPS2069D in a USB battery charger circuit. The input is standard +5V DC and I intend to charge 3 NiMh cells at around 400mA using a linear constant current charger. The TPS2069D is used to isolate the battery from the charging circuit when the USB power supply is disconnected and so prevent the battery discharging into the charger. I cannot use a diode to prevent back feeding of current as there is not enough voltage available for the diode drop. My question is: If the input to the TPS2069D is close to 0V (i.e. USB disconnected) and the output is at about 4V (i.e. connected to the battery) will significant current flow back into the TPS2069D from the battery and so discharge it? I am assuming the TPS2069D is disabled.

Thank you.

John

  • 0
    TI__Expert 8980 points
    Hi, John,

    Sorry for late reply because I had a urgent case last week.

    You are correct, when TPS2069D Vin is close to 0V(as long as it's below Vuvlo=3.36V), TPS2069D will be disabled, so there will not be significant current flow back.

    Feel free to ask if any questions.

    Regards,
    Bob
  • 0 in reply to Bob Ma
    Prodigy 20 points
    Thank you Bob,
    I originally used a Diodes Inc. device AP22814AW5-7 due to its higher current rating, but it did not perform as expected. The reverse current was 30mA which would have quickly drained the battery although the data sheet suggested it would have been in the uA region, hence I checked with you before trying the TI device. This is pin for pin compatible with the original Diodes Inc. device, but it works!
    Best regards
    John
  • 0 in reply to John Ruby
    TI__Expert 8980 points
    Hi, John,

    Glad to hear that. Thanks for your interest, fell free to ask if any questions.

    Regards,
    Bob