Power supply for microcontroller!!!!

[W_Heisenberg]

I now have a voltage supply, it is actually made by capacitor. That is to say, the voltage is not stable. For a microcontroller, I think Vdd should be stable. Thus, if I use this supply, microcontroller will fail to work. Is this true?

 

[karthikkrv85]

When you supply unstable power to microcontroller, it wont fail to work, until or unless the supply crosses the maximum supply range of micro controller.

Think that all your microcontroller's internal peripherals are connected with that particular voltage (Vdd). When you feed unstable supply and if you want to get a output from a port pin, that also oscillates as per the supply. So the connected peripherals may or may not recognize the correct logic and misinterprets the output. That intern affect your whole system's functionality and purpose.

And you can not guarantee that your supply will not go above or below the required range of operation. This is the main reason you need a stable voltage supply or regulated supply

Thanks

 

[Tahmid]

Your microcontroller won't "fail" unless you burn it by crossing its maximum voltage or it turns off if the supply voltage is below the minimum voltage.

But you will have problems. Eg. If the ADC uses this as the reference voltage, as your voltage fluctuates, so does the ADC output. Then, it becomes difficult to interpret this result.

Also your output voltage from the microcontroller will vary with the changes in power supply voltage.

There are many more possibilities. Your circuit will "malfunction". So, you should just use a regulated supply. All it would take to regulate your supply is a regulator and a few capacitors. You can use a 7805 if your input voltage isn't too high.

A simple circuit like this will do:

Hope this helps.
Tahmid.

 

[shahbaz.ele]

you must have regulated supply for your circuit.

some mcontroller may work(having range 3.3V to 5V) but results are not grantteed