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This is the datasheet of 7805 voltage regulator produced by "Continental Device India Limited".

Question:

  • Why is the peak output current greater than short circuit output current?
  • Shouldn't the short circuit output current be greater than the peak output current since at short circuit resistance is zero and maximum current will flow?

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    \$\begingroup\$ Please add a link into your question - not in the comments - to the complete manufacturer's datasheet. \$\endgroup\$ – Transistor Feb 1 '19 at 16:00
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    \$\begingroup\$ It's also possible the regulator implements foldback to protect itself from excessive power dissipation. \$\endgroup\$ – Brian Drummond Feb 1 '19 at 16:11
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    \$\begingroup\$ It is hard to say. Because one is continuous and one is transient. Because the regulator has fold-back current limiting (no reason it couldn't!). Because a 7805 is typically thermally limited (but you can't count on that if it's not from one of the original manufacturers). Typically the LM7805 is a very robust beast; it's hard to let the smoke out of them without reversing polarities or putting too high of voltage on them. I don't know that I would trust that robustness from some new semiconductor company. \$\endgroup\$ – TimWescott Feb 1 '19 at 16:13
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Those are two very different things measured in different situations.

Short circuit current is what comes out from the regulator when its output is shorted to ground, so the output voltage is zero. So regulator protects itself by limiting current.

Peak output current is the maximum current what the regulator can drive into load when output voltage is regulated to the nominal 5V voltage. This requires that the input voltage and temperature are within some optimal range, or there will be less current.

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as some had mentioned, the 78xx has an internal current-limiting circuit, this is configured to detect when it's output operates outside it's intended parameter. this function also allows it to operate as a current regulator.

you can look into the schematic of 78xx. https://www.sparkfun.com/datasheets/Components/LM7805.pdf

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