the transformer circuit is the first stage of a dc power supply.
the transformer circuit is the first stage of a dc power supply.
which circuit is the first stage of a dc power supply?
transformer
if the smps has an ac input, then the first stage is to convert the input to dc. this is called "rectification". an smps with a dc input does not require this stage. in some power supplies (mostly computer atx power supplies), the rectifier circuit can be configured as a voltage doubler by the addition of a switch operated either manually or automatically. this feature permits operation from power sources that are normally at 115 v or at 230 v. the rectifier produces an unregulated dc voltage which is then sent to a large filter capacitor. the current drawn from the mains supply by this rectifier circuit occurs in short pulses around the ac voltage peaks. these pulses have significant high frequency energy which reduces the power factor. to correct for this, many newer smps will use a special pfc circuit to make the input current follow the sinusoidal shape of the ac input voltage, correcting the power factor. power supplies that use active pfc usually are auto-ranging, supporting input voltages from , with no input voltage selector switch.
switched-mode power supply
section::::types.









































section::::types.:dc power supply.









































a dc power supply is one that supplies a constant dc voltage to its load. depending on its design, a dc power supply may be powered from a dc source or from an ac source such as the power mains.









































section::::types.:dc power supply.:ac-to-dc supply.
power supply