All electronic circuits need a dc power supply for
their operation. To obtain this dc voltage from 230 V ac mains supply, we need
to use rectifier.
Therefore the filters are used to obtain a ―steady‖ dc voltage from the pulsating
The filtered dc voltage is then applied to a
regulator which will try to keep the dc output voltage constant in the event of
voltage fluctuations or load variation.
We know the combination of rectifier & filter
can produce a dc voltage. But the problem with this type of dc power supply is
that its output voltage will not remain constant in the event of fluctuations
in an ac input or changes in the load current(IL).
The output of unregulated power supply is connected
at the input of voltage regulator circuit.
The voltage regulator is a specially designed
circuit to keep the output voltage constant.
It does not remain exactly constant. It changes
slightly due to changes in certain parameters.
affecting the output voltage:
IL (Load Current)
iii) T (Temperature)
basically series regulators with all the basic blocks present inside the IC.
Therefore it is easier to use IC voltage regulator instead of discrete voltage
features of IC Regulators:
Facility to boost the voltage/current
Internally provided short circuit current limiting
Floating operation to facilitate higher voltage