voltage regulators!!

[ali ghafoor]

if some voltage regulator has maximum output current rating of 1 ampere(e.g 7805); can it provide 1 amp at the output even when the input supply to the regulator is not capable of providing 1 amp?? reply pls..

 

[tpetar]

if some voltage regulator has maximum output current rating of 1 ampere(e.g 7805); can it provide 1 amp at the output even when the input supply to the regulator is not capable of providing 1 amp?? reply pls..

What to say on this?

7805 cant give 1A current from nothing, regulator needs enough current and at least 2,5-3V voltage higher on input. For now we dont know how to make current from vaccum.

Also check datasheet for 7805 regulator to see in what case you can get 1A.

Probably "input supply" will be damaged if there is no fuse as protection.

 

[andro]

Think of a transformer rated as 9V/2A, after rectification the current will be reduced to for example 1.95 Amps then that is the max DC current can be supplied by the power supply. If you connect it with 3 Ohms resistor how much current will be delivered to the load?
By ohm's low 9/3 = 3 Amps it is exceeded by 1, then the load will be loaded on the power supply, and power supply will be heated. for this reason the designer put fuse and Varistor to protect the power supply from short circuit and overload.

 

[Tahmid]

if some voltage regulator has maximum output current rating of 1 ampere(e.g 7805); can it provide 1 amp at the output even when the input supply to the regulator is not capable of providing 1 amp?? reply pls..

The 7805 is a linear regulator. For linear regulators, the input supply must be capable of supplying the maximum output, as, for linear regulators, Iout = Iin.

Hope this helps.
Tahmid.