5v power supply

[samtheboxer]

regarding a power supply for a pic 12f629. a LM7805 is too big, im looking for something smaller. Is there a surface mount 7805? or is there another way to build a smaller circuit (im trying to get it all about the size of a nickel, maybe)

 

[Sceadwian]

What's your input voltage, and how much current are you going to need? A zener diode and a resistor are good for basic situations as long as the voltage you're dropping isn't too large, less than the size of a dime.

 

[samtheboxer]

What's your input voltage, and how much current are you going to need? A zener diode and a resistor are good for basic situations as long as the voltage you're dropping isn't too large, less than the size of a dime.

the voltage would be 12v with a 3 cell lipo battery. it will power a 12f629 flashing different light patters, it will then monitor the power supply and change flash patterns when it drops below 9.8 volts.

 

[audioguru]

A 78L05 comes in a TO-92 small transistor case and two surface-mount packages. It can supply up to 100ma.

 

[Hero999]

What's your minimum and maximum input voltage?


If it's a 9V battery and you only want 50mA then go for the LM2936-5.0 as it has a lower output voltage and a lower quiescent current.

 

[mvs sarma]

What's your minimum and maximum input voltage.


If it's a 9V battery and you only want 50mA then go for the LM2936-5.0 as it has a lower output voltage and a lower quiescent current.

You mean low dropout voltage?

 

[Hero999]

Yes, I meant lower dropout voltage than the LM7805.

 

[audioguru]

The 7805 needs a minimum input voltage of about 7.5V.
But a 9V alkaline battery's voltage drops quickly to 7.2V which is too low, then drops more to 6V.

A rechargable "9V" battery is frequently actually 7.2V.

So a low-dropout regulator is needed.