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And a normal 5V regulator like the 7805?
And a normal 5V regulator like the 7805?
Whats the difference between these two voltage regulators?
- Thread starter sputz
- Start date
The 7805 is a linear regulator which basically means that it just "chopps-off" the excess voltage to give you want you need. The voltage drop times the current though the regulator gives you the power that must be dissipated by the regulator, which can end up being very large if you have a very high input voltage and a relatively high output current as the amount that needs to be "chopped-off" is very large.
The modules you have linked to are switching regulators which use an inductor to store and regulate the flow of energy. In this way, although the system is much more complex to design, efficiency of the system can be much higher. Information about the chip upon which the module is based can be found here: http://www.national.com/mpf/LM/LM2575.html.
ylp88
The modules you have linked to are switching regulators which use an inductor to store and regulate the flow of energy. In this way, although the system is much more complex to design, efficiency of the system can be much higher. Information about the chip upon which the module is based can be found here: http://www.national.com/mpf/LM/LM2575.html.
ylp88
Switching regulators use energy more efficiently but it may or may not be worth the extra cost. Say you had a 20V supply and you wanted 5V at 1 amp. An ordinary 5V regulator would draw 1 amp at 20V or 20 watts. It would also throw away 15 watts in heat (not very 'green') which needs a bigger heatsink and the heatsink would probably cost more than the switching module.
If a switching module were 100% efficient it would draw only 0.25 amps from the 20V supply to produce 1 amp at 5V. In reality it is about 90% efficient so maybe 0.28 amps. It also hardly gets warm so doesn't need a heatsink. Compare 1 amp at 20V vs 0.28 amps at 20V and you can see how the switching regulator uses less power.
So for this application a switching regulator is a much better choice.
But say you were running a picaxe at 3mA. The power saved really isn't worth the extra expense as no heatsinks are needed. You would probably use a 78L05 which is only good for 100mA but is cheaper.
Or say you didn't have a 20V supply. Say you had an 8V supply. The extra expense of a switching reg probably isn't needed.
It depends on your input volts, whether you can change that or whether it is fixed, and your output current. What is your application?
If a switching module were 100% efficient it would draw only 0.25 amps from the 20V supply to produce 1 amp at 5V. In reality it is about 90% efficient so maybe 0.28 amps. It also hardly gets warm so doesn't need a heatsink. Compare 1 amp at 20V vs 0.28 amps at 20V and you can see how the switching regulator uses less power.
So for this application a switching regulator is a much better choice.
But say you were running a picaxe at 3mA. The power saved really isn't worth the extra expense as no heatsinks are needed. You would probably use a 78L05 which is only good for 100mA but is cheaper.
Or say you didn't have a 20V supply. Say you had an 8V supply. The extra expense of a switching reg probably isn't needed.
It depends on your input volts, whether you can change that or whether it is fixed, and your output current. What is your application?