Hi guys,
I have a question about filter capacitor size in power supplies. So if you look at the datasheet on a regulator like the 7805 or something, they always say put a 0.1uF cap on the input if it is more that 6 inches away from the regulator. So basically you see caps like 0.1uF, 10uF, 22uF, etc... used to filter out transients in the voltage at either the input or output stages of the regulators.
I'm wondering how the size of the capacitor affects the transient rejection performance. If I put a very small cap, say 1pF that means the cap will not have enough energy to stabilize the voltage if it drops for a few milliseconds right? So a bigger cap is better for this purpose? Lets say I replaced it with a 1mF capacitor, will that be much better at rejecting transients or will that cause other problems?
I tried looking around but couldn't find anything definitive.
BTW, I'm not talking about the smoothing capacitor. I don't know if these transient filter caps have a better name than simply filter capacitor.
Thanks.
I have a question about filter capacitor size in power supplies. So if you look at the datasheet on a regulator like the 7805 or something, they always say put a 0.1uF cap on the input if it is more that 6 inches away from the regulator. So basically you see caps like 0.1uF, 10uF, 22uF, etc... used to filter out transients in the voltage at either the input or output stages of the regulators.
I'm wondering how the size of the capacitor affects the transient rejection performance. If I put a very small cap, say 1pF that means the cap will not have enough energy to stabilize the voltage if it drops for a few milliseconds right? So a bigger cap is better for this purpose? Lets say I replaced it with a 1mF capacitor, will that be much better at rejecting transients or will that cause other problems?
I tried looking around but couldn't find anything definitive.
BTW, I'm not talking about the smoothing capacitor. I don't know if these transient filter caps have a better name than simply filter capacitor.
Thanks.