<P> If the SMPS has an AC input , then the first stage is to convert the input to DC . This is called rectification . A 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 ~ 100 VAC -- 250 VAC , with no input voltage selector switch . </P>
<P> If the SMPS has an AC input , then the first stage is to convert the input to DC . This is called rectification . A 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 ~ 100 VAC -- 250 VAC , with no input voltage selector switch . </P>
which circuit is the first stage of a dc power supply
which circuit is the first stage of a dc power supply
the rectifier circuit
the rectifier circuit