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Power supply fluctuations. Bypass capacitor needed?

I am powering up a 5V device using a 12v DC 1A SMPS power supply. The 12V supply is connected to the 5V device through a 7805 voltage regulator. The device draws about 30mA when idle, but when it ...
John918's user avatar
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6 votes
2 answers
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What is the purpose of the 7805 output capacitor?

How does a cap on a regulator output improve transient response? Is this cap not more appropriately drawn next to the load where it is not being defeated by intervening trace inductance? Or does this ...
mhz's user avatar
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6 votes
5 answers
6k views

What is the purpose of the 7805 input capacitor?

Most 7805 datasheets specify an input capacitor of 0.33uF or so. This one (the LM340 http://www.ti.com/lit/ds/symlink/lm340-n.pdf) at least specifies that the cap is only required if the regulator is "...
mhz's user avatar
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