Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
MrNobody said:Just wondering.. what is the general rule tor selecting capacitor for voltage regulators..? is there a formula for calculating it..? is it like, the higher the capacitor value is the, the better it is because it can filter out more noise..?
MrNobody said:dknguyen:
Actually, its for the ENC28J60 ethernet controller..
The requirement is 3.3V..
I am using LM1117T voltage regulator..
According to the datasheet, the V(in) capacitor is 10uF and V(out) capacitor is 10uF.. however, according to the ENC28J60 board schematic, the V(in) capacitor is 0.47uF and V(out) capacitor is 47uF. The V(in) voltage is 5V..
If I don't have 0.47uF and 47uF capacitor, can I use other capacitor..? I have 0.1uF (many), 10uF (only 1) and 100uF (only 2)..
Another thing is, currently, i am feeding the LM1117 (3.3V regulator) from the output of LM7805 regulator.. At the same time, the 7805 regulator is also supplying voltage to a microcontroller circuit.. Is that OK or should I feed the 3.3V regulator directly from power 9V supply/battery..?
It should be OK because the LM1117T is a low dropout regulator and will work down to 4.5V input with 3.3V out at 800ma in the worst case scenario. Now if it was a typo and you meant LM117, then no, you'd need to run it directly from the 9V supply.MrNobody said:Another thing is, currently, i am feeding the LM1117 (3.3V regulator) from the output of LM7805 regulator.. At the same time, the 7805 regulator is also supplying voltage to a microcontroller circuit.. Is that OK or should I feed the 3.3V regulator directly from power 9V supply/battery..?
I would go by the LM1117Ts datasheet as far as the input and output decoupling caps are concerned. You can always go higher in uF than the datasheet, but don't skimp on the low side.According to the datasheet, the V(in) capacitor is 10uF and V(out) capacitor is 10uF..
Why don't you read the datasheet for your LM1117 regulator?Actually i don't have 47uF. can I use 10uF on the input and 100uF on the output instead?