Hi All,
I was using a buck regulator to generate 2.8 Volts from 3.3 volts. Now i need 3.3 volts output. Can I use the same buck regulator with the same input voltage of 3.3 volts.

regards
sharath

 

Not really, any real switch will some small voltage drop across it. What is the reason you need a regulator? At those small voltage differentials you can often use an LDO (still has a small V drop from input to output).

 

It depends on the circuit. If there is some reason you can't use the existing 3.3v directly you'll have to find a circuit that can do that or put your circuit here so we can take a look at it.

http://www.hills2.u-net.com/electron/smps.htm#buck

 

A SEPIC converter has the possibility to have its input either above or below the output voltage. Is it right for you? Hard to say without knowing your requirements.

A 3.3 Volt LDO will need at about 3.45 V on the input for 150 mV LDO. Your mileage may vary.

 

Thanks for the sugesions:
Actually I am using Power Management unit which takes 3.3 volts. This PMU gives out other supplies. As mrmeval said I think we can use the 3.3 volts directly from the source.

regards
sharath

 

Or a buck boost could do it.

 

Charge pump regulator can do it . Sometime we can't use 3.3V directly due to locked up on the digital circuit if for some reasons it falls out of V specs. The regulator can help it stay in 3.3V . Sorry for my English . Kinda to old to learn to write it correct .