How does Switch mode power supplies differ from diode rectification

[peejake]

hey guys,

the topic basically explains it...Can someone please help me out with this question...How does SMPS differ from diode rectification?

Thanks

jake

 

[Hammie]

Typically, a SMPS does not rectify anything. The switching device is turned on and off at precise intervals to either charge a capacitor to a desired voltage, or to drive the primary winding of a transformer in such a way as to produce a constant voltage derived from a secondary winding.

The switching element is switching a DC source on and off.

A diode rectifies by switching on for half a cycle of a AC source, and switching off for the other half.

this is a pretty good short article on SMPS's

http://en.wikipedia.org/wiki/Switched-mode_power_supply

 

[berkeman]

A SMPS is a DC-DC converter, optionally with a diode bridge input stage if the input is an AC source. The DC-DC converter can be isolated (where the input and output stages are separated by a transformer), or non-isolated (where the input ground is connected to the output ground).

All DC-DC converters use a reactive energy storage element in their conversion of the input voltage to the output voltage. Most commonly, an inductor or transformer is used as the reactive element. In some cases, capacitors are used (like with the MAX232 chip for RS-232 communication interfacing, or for on-chip charge pumps for flash memory writes).

Does that help?

 

[peejake]

thanks for the link hammie...it was great

Berkeman thanks for that too...I was able to understand the 1st paragraph but not much of the second...It made sense though...

thanks