Neil Powell

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12 years, 10 months ago.

Voltage regulator

Hi! I am new in using LPC1768. I have a problem on build a regulator for my microprocessor input. I have several inputs(12V DC, 14V AC and 24V AC) which are too high for LPC1768. Can I connect a 7805 5V regulator to my microprocessor? Or I need to build a voltage transformer by myself? Any advice?

Thank you very much!!!

1 Answer

Erik -
12 years, 10 months ago.

One option is to connect the mbed directly to the 12V DC. Yes that is above the rated maximum, however that is only due to power dissipation: If you are sure you don't use much power it is workable (see: http://mbed.org/forum/mbed/topic/127/). Your solution is a bit nicer, you can indeed simply use an 7805 (dont forget its capacitors) and connect it to Vin of the mbed.

Accepted Answer

Thank you for your advice. You have mentioned capacitors. Do I need to solder additional capacitors on 7805 and then to mbed?

posted by Neil Powell 07 Nov 2012

The minimum would be to put a 100nF cap on the output of the 7805. However, if you have some caps about I would suggest putting an additional 10uF cap on the 7805 output and a 100nF cap on the input to the mbed. You can (almost) never have too many caps!

posted by Martin Smith 07 Nov 2012