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LP2985 efficiency

Francois Dupont
Prodigy 40 points
Other Parts Discussed in Thread: LP2985

Hello,

I would like to use the LP2985 (fixed output 5V) to power on a electronic circuit.

The input of this regulator would be 12V and the circuit consumes around 50 mA.

I would like to know the input current of the regulator. I can't find this information in the datasheet, but maybe I'm too tired ;)

Thanks for your help,

Br

  • 0
    TI__Expert 8890 points

    By far the largest component of the input current goes to supplying the output current from Vout.  But there is also a component of the input current that powers the internal control circuitry.  This "control" current is the only current that returns through the ICs ground pin - referred to as "Ignd" in the data sheet, page 5. Therefore  the data sheet records the Ignd current for various loads and operating conditions.  For a load current (from the Vout pin) of 50mA the Ignd=350uA (typical) according to the data sheet.  In conclusion the efficiency is then usually calculated as Eff = (Vout x Iload) / (Vin x (Iload + Ignd)).  If Ignd is negligible than Eff = Vout/Vin