Power supplies for microcontroller based projects

Posted on Feb 6, 2014

Here we are working on small microcontrollers like PICs and Atmel series, which are operating from 5V and require less than 100mA for complete system typically. There are some PICs operate from lower voltages like 3. 3V, but the principals for power supply are almost the same. This article covers power supplies with low power output which is suitable as simple source of reliable low voltage power for the microcontroller based projects.

Power supplies for microcontroller based projects
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If you need currents higher than 1A to operate your circuit, you need high power capable power supply. When developing circuits unexpected accidents are not uncommon. For an example short circuit due to Solder Bridge or a wire placed in wrong hole are mostly seen. If your power supply is not current limited and has rated few Amps, then these accidents can course severe damages to you and your valuable project. So always using current limited power supply is good idea. It is recommended to use power supply based on 7800 series regulator for small microcontroller based project. 7805 regulator is widely used cheap and reliable solution which will out put regulated +5V on its O/P terminal. A good power source would be 12V 500mA power pack which is powered by mains power outlet. The regulator should not be too much larger than actual expected current demand of project. When estimating power, calculate as 5mA for MCU chip, about 3 mA for TTL/CMOS ICs, 10mA for regular size LED etc. Always refer datasheets of your parts to find out their operating standard and peak currents and make power supply rated to peak operating current of project. For a load of 50mA or less use a 78L05 which is rated at 100mA but will deliver a bit more. If you need more than 50mA for your circuit, 7805 regulator can supply about 1A with heat sink on it. Having series diode in the +ve line before the input capacitor is good idea because this protects power...

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