Originally posted by anybisi@Mar 7 2006, 06:47 PM
pls, i need to convert 48 volts DC to 12 or 24 DC,
[post=14759]Quoted post[/post]
You could try one of National Semiconductor SMPS chips. The cct will be a little more complex but power dissipation is a lot less for the same current output. The NSC site has a great workbench function where you can design it on the web and actually tells you the parts you need to go with it.Originally posted by Gadget@Mar 8 2006, 09:02 PM
Some major problems using an LM7812.
The 1st is that the Maximum specified input voltage is 35 volts for a LM7812, and 40volts for the 7824 (24 volt version) so you would need a Pre-regulator, or some method to drop the input voltage down to a safe value for the regulator to operate at.
The next is (as hgmjr said) power dissapation. Just getting a modest current flow is gonna turn the regulator and pre-regulator into heaters.
Related to the above is efficiency. Going from 48 to 12 with a linear regulator means that 75% of your power is being wasted.. (as heat...see above).
You don't mention what current is required, or what the application is so it is hard to recommend what to use.
My choice, for most higher current applications (with the exception of powering a sensitive radio reciever) would be Switch Mode regulation, which involves generating a square wave with a mark space ratio of 1 to 3 and lots of filtering (with perhaps some feedback to adjust the mark space ratio for voltage regulation). This would give good efficiency and low heat dissipation and potential for good current ratings (depending on design). The main dissadvantage is the potential for noise on the output.
[post=14770]Quoted post[/post]
Linear Technology has LTSpice/SwitcherCADIII.Originally posted by anybisi@Mar 7 2006, 07:47 PM
pls, i need to convert 48 volts DC to 12 or 24 DC,
[post=14759]Quoted post[/post]
price is not an issueOriginally posted by thingmaker3@Mar 8 2006, 11:25 PM
What's the budget?
http://www.zahninc.com/sd1.html
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Originally posted by anybisi@Mar 8 2006, 05:17 AM
pls, i need to convert 48 volts DC to 12 or 24 DC,
[post=14759]Quoted post[/post]
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