How much current does a IC7805 regulator draws, when it drives a 1.5A load?


closed as off-topic by Bence Kaulics, Voltage Spike, Autistic, ThreePhaseEel, Daniel Grillo Nov 23 '16 at 10:38

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    \$\begingroup\$ Linear regulator's Input current = Load current + Quiescent current (listed in datasheet). \$\endgroup\$ – MarkU Feb 8 '16 at 7:26
  • \$\begingroup\$ Welcome to EE.SX Vishruth! Always look at the device datasheet, 99 times out of a hundred the answer will be in there. \$\endgroup\$ – rdtsc Feb 8 '16 at 23:23
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    \$\begingroup\$ I'm voting to close this question as off-topic because the answer is in the datasheet and people need to do research before posting \$\endgroup\$ – Voltage Spike Nov 22 '16 at 18:00

The LM7805 has a GND current that is almost invariant with output current.

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Note that this is not always true. There are some old and hopefully mostly forgotten bipolar linear LDO regulators that have a huge spike in current draw for low input voltage and high current. The LM2941 is one such part:

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Edit: The current going into a linear regulator is the output current plus the Iq, as MarkU says. Iq is negligible near full load current (for a 7805) but at low current (say 1mA) most of the current is used in the operation of the regulator.

If you are operating anywhere near 1.5A continuously you should toss the 7805 and use a switching regulator. The power waste is huge- not from Iq but from the fact it's a linear regulator and can't have reasonable efficiency.


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