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LP5912: Iq/Ig

Umberto Frangi
Expert 4045 points
Part Number: LP5912


Hi,

 in the datasheet there is a spec for Iq with max at 55/600uA max and then another for Ig at 35uA typical.

What is the difference between Iq and Ig and what are the conditions for the specifications?
Thanks

Umberto

  • 0
    TI__Expert 4065 points
    Hi Umberto,
    Iq is the Ig when no load is connected to LDO while applying the same input voltage, Iq will change as load is applied to LDO where the internal circuity of the LDO consumes more current to operate.
    The datasheet specifies the conditions of measurements (Vin, Vout, Cin, Cout, and Iout) for both Iq ang Ig at the top of EC table section 7.5

    BR,
    Haidar
  • 0 in reply to Haidar Hamoo
    TI__Expert 4045 points
    Hi Haidar,
    then Ig should be equal to Iq at Iout=0 and I do not understand why we need to specify it in the datasheet.
    Also there is a difference as Ig=35 uA typical and Iq at Iout=0 is 30 uA typical.
    Is the above correct?
    Thanks
    Umberto
  • 0 in reply to Umberto Frangi
    TI__Expert 4065 points
    Hi Umberto,
    My apology for the delayed response but I had to do physical measurement to verify my answer regarding LP5912 device, the 30uA Iq at no load condition is correct and the 35uA ground current (Ig) is a typo and should be 30uA.
    We typically specify ground current in the datasheet and not quiescent current, I am not sure why both currents were mentioned.
    Again my apology for the delayed response!

    BR,
    Haidar
  • 0
    Intellectual 515 points

    For LP59xx family (LP5912 included) 'IQ' is the difference between IN pin current and OUT pin current for a given load current (Iout). See Note 6 on the EC table page.

    Thus 'IQ' does NOT include pull-up current through the EN pin to the ground pin, or any leakage current through the PG pin to the ground pin.

    The 'IG' current is measured at the GND pin and will be the sum of Iq, Ien, and Ilkg(pg). See note 7 on the EC table page.

    As a result  the 'IG' current will always be higher than the 'IQ' current , albeit only perhaps a few micro-amps higher (mostly by Ien).

    For most users the distinction is of no real value, however there is some value for some users.

  • 0 in reply to Daddio
    TI__Expert 4065 points
    Thank you Daddio for your further explanation, the measurement with EN pin tied to VIN where I got 30uA of current through supply with no load connected. As for EN pin current, with no load, EN pin current that I measured was 500nA.
    Again thank you for your explanation.
    BR,
    Haidar