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LM3671: High current consumption when Vin <= 3.3V

Alex Nic
Prodigy 10 points
Part Number: LM3671

Hello!

I'm using LM3671MF-3.3/NOPB to power ESP12-F. When input voltage (Vin) greater than 3.3V and ESP-12F goes to deep sleep, everything is fine, i have about 50uA current consumption. But if Vin is less or equal to 3.3 V, the current increases to 330-400uA. Is it normal for LM3671MF-3.3/NOPB?

  • 0
    TI__Genius 17810 points

    Hi Alex,

    When the input is higher than 3.3V, the device could be in PFM mode with less frequent switching cycles. Bringing the VIN closer to VOUT would cause it to switch more and finally get into 100% mode where the high side FET is fully turned on. The input current consumption will get higher when VIN gets closer to VOUT. What is the load current here? 

    Best regards,

    Varun

  • 0 in reply to Varun John
    Prodigy 10 points
    Varun John said:
    What is the load current here? 

    Hi Varun,

    The load current is about 20 μA.

  • 0 in reply to Alex Nic
    TI__Genius 17810 points

    Hi Alex,

    Thanks. Since the load is so low, it looks to me the higher input current is due to internal current consumption when the device first gets into PWM and then 100% mode.

    Just to make sure the load current isn't higher than 20uA, could you please disconnect all loads on the output rail and check the input current consumption for VIN <= 3.3V?

    Best regards,

    Varun