adnan_m_s said:
Guys!
Could I ask what is the difference between switching power supply and regualted power supply please?
could you provide some IC names or how the circuit is designed to be switch power supply which produces less heat?
Adnan
A simple way of thinking of a switching power supply is that it takes small bites of input power and integrates them (with a coil and a capacitor) into a constant voltage. Power disipation in this mode is very low as power is consumed only when taking a bite
Sorry... that analogy probably went too far. Suffice to say a switcher is active only part of the time, and hence the heat output is *greatly* reduced.
As an example, I recently needed 5v from a 21vdc source at just 200mA. A linear 7805 regulator gets very warm dissipating some 16v to get me 5v and a large heatsink was required despite the low current being drawn. I'm now using an LM2595T-5.0 from National Semiconductor and it requires no heatsink whatever and barely rises above room temp.
NatSemi has plenty of design tools on the web for helping you design a switchmode, and will even create a parts list for you, so they are *simple*!! My circuit has an LM2595, a schottky diode, an inductor, and a main capacitor, plus the usual assortment of small .1uF monolythic caps for removing high frequency switching noise from both the switcher and the other components.
Look here:
**broken link removed** for the web tools to design a switching supply.
Switchmodes are also able to increase an input voltage to a higher one, albeit at lower current than the input side. A switchmode that drops voltage is called a "buck" convertor, one that increases the input voltage is called a "boost", and one that can do both (e.g. for running off batteries) is called a "buck/boost".
Hope that helps,
P.