Electronic – Selecting the correct input/output capacitors for a 7805


So I've got a 7805 Regulator and I've been looking it up and each website says different info. I am using an input of 12V DC 1A Wall Adapter as an input supply.

  • www.adafruit.com Says

    This regulator does not require capacitors for stability.
    We recommend at least 10 uF electrolytic capacitors on both input and output.

  • Datasheet Says

    0.33 uF into the input pin and a 0.1 uF into the output pin.

so I want to know which is better and if it matters. I am looking to make it stable to charge electronics and supply projects and such.

Best Answer

Obey the datasheet, but there is no harm in adding extra capacitors.

The 330nF and 100nF (non-electrolytic) capacitors are probably required to guarantee that the regulator is stable. They should be as close to the regulator as possible.

The 10µF electrolytics suggested on the website may be beneficial to the rest of the circuit. Eg. ripple smoothing on input and a "circuit-wide" decoupling on output.

So, I'd suggest combining the two. (Don't use just the electrolytics as they have strong parasitic properties.) If space is limited, I'd go with what the datasheet says only.


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