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Voltage Regulator advice required

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I'm planning to use a Recom R-785.0-0.5 http://www.electro-tech-online.com/custompdfs/2009/04/R-78xx-10.pdf
switched regulator to convert a nominal 7.4V from a LiPo battery to a 5V output, to power the Rx & servos in a RC model glider

I have been told I need the following capacitors on the input & output sides
.. simply solder a 100uF on the input and 10uF output

Are these caps. necessary for an application such as this?
Do the values sound about right? - how does one calculate the values required? is there a rule of thumb / design criteria for this

Thanks, Geoff


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Most Helpful Member
My reading of your referenced spec sheet suggests to me that for a single regulator no bypass caps are required, just suggested. The ones they talk about being required are related to their example where the 78xx is combined with a switching converter. Note that in their two examples, only the capacitor between the switching converter and the regulator is tagged as being needed. In both examples, the capacitor on the other end is suggested, but not required.

In your application, you might want the 100uF one on the servo motor side because those servos are pulsed on/off internally, and they spike large currents (~1A) when they turn on, so they in-effect behave like their switching converter. No capacitor on the input to the reg.
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