- kmn wrote:
- Hi Friend,
Yeah,I'm Kyi Min Naing.
O/P DC Voltage Adaptor mean that Output DC voltage Adaptor.Found that Switching adaptor is better than Linear Adaptor for most of electronic communication devices that has needed to supply InPut DC voltage.Switching adaptor can synchronize built-in power supply delivery circuit components on PCBA .It can adjust with the performance of CMOS LDO (Low-DropOut) voltage regulator and prevent the damage of LDO regulator when use in long time continus.
So,I post the previous questions on forum.I want to robust about it.If it is robust,our friends can solve most of problem communication devices (ADSL Modem) in myanmar after replacing with the same switching adaptor. 
Thanks
Hay KMN ,
What you said is right . Basically SMPS ( switch mode power supplies ) are better than Linear ones. Their advantages are :
1. they have wider input ranges ( which is particularly siuted for myanmar) whereas linear regulators are not economically possible for wide range inputs because all the regulated voltages are dissipated in the IC ( LDO or ordinary or whatever).
2. SPMS have higher efficiency compared to linear ones because most of the energy losses are in transformers and switches ( FET or BJT or IGBT or similar ). These semiconductor switches have two type of loss namely resistive loss and switching loss. Resistive losses are normally smaller and smaller with low Ron switches FET. Switching losses need careful attention since they get much higher with increasing frequency. Under todays atmosphere,
life can be easy . Compaies such National semiconductor makes special ICs for SMPS . They are quite good that EC engineers are left with little work to do.
Now...
SMPS means switching which is not always a good thing. First of all they need a better and smarter closed loop control. They normally require more components than linear regulator and so they are more expensive.
SMPS also suffers from switching fatigue and turn-on/off stresses.
One more thing.
Switching circuit can and do radiates electromagnetic energies from such things as components and PCB traces. Some times it is strong enough that is not suitable for some use. Let's say if a SMPS is radiating some RF frequencies which affects a heart pumping and monitoring machine of a very sick patient , it would be a big problem. Right ? So EMC clearance again becomes important( I mean not in myanmar) Linear supplies doesn't have such problem.
I think SMPS will be good enough for ADSL devices for use in mm.
ur friend
Subject: What is the distinguishing of Switching & Linear adaptor 
Wed Oct 25, 2006 4:01 pm