[SOLVED] [Moved] dc-dc buck converter 200V input 3-5W

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sabu31

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Hi

I need to know some companies which sell dc-dc converters (buck ) whose input can vary from 75-200V and gives +- 15V at around +-200mA. The best i could find is from tracopower whose dc-dc input can be up to 160V.Thanking you.

Not related to microcontrollers. Moved to power electronics [alexan_e]
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Go to the website of RS Components, one of the largest traders of electronics/electrical products, search with your specification and find the exact product.
 

I doubt you'll find a buck converter with those specs, since buck isn't a topology suited to those input/output specs. Do you actually care what topology it uses, or just that it has those input/output specs?
 

sabu31 said:
Hi

I need to know some companies which sell dc-dc converters (buck ) whose input can vary from 75-200V and gives +- 15V at around +-200mA. The best i could find is from tracopower whose dc-dc input can be up to 160V.Thanking you.
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if you use buck with such a high input voltage the duty cycle of mosfet/bjt will be too low for its proper operation. that is why you would have to first step down the input voltage via ferrite transformer and then filter and regulate it on secondary side. now you will also have adequate duty cycle for proper operation. i.e. use transformer based topologies.
 

I actually want readily available step down converter which should be able to give +-15 at +-500mA ( input being 75-200V). I checked in RS components and element 14 . The best i could find is having input upto 160V. Using two stage is also an option however i want the first stage to be able to step down from 200 to atleast 75(at say about 15W).
 

You will probably have trouble finding something off the shelf, mainly due to the input voltage range (which is kind of in a no-man's land between 48V industrial supplies and 300-400V offline converters) and the low power requirements (most supplies with high voltage inputs will be specced for 30W or more).

So either you'll probably either have to contract a custom supply to be designed, or use a two stage approach. Personally I would us a dirt simple DC transformer circuit to step the input down by a factor of 3 or 4 as the first stage, then use a more typical step down converter.
 

Ok mtwieg .. that could be the reason that i am not able to find dc-dc converter in that range. What did u mean by dc transformer circuit. Is it full bridge converter that u meant.?
 

A DC transformer is a circuit that implements a step up or step down of DC voltage. There's generally no feedback or regulation, but they do isolate (if you want). They can be made to self oscillate with few components. It's a pretty old technique, and you used to be able to find modular ones pretty easily, not so sure about now. But it's the simplest solution to your problem (aside from making a custom single stage converter).
 

+-15 V at +- 200 mA is, in terms of power, 30 V * 0.2 A = 6 W instead of 3 - 5 W.

There are not many (common and easily available) DC/DC with the specs you are talking about, however, a standard AC/DC (85 VAC to 265 VAC) compact converter may be operational with a DC power supply at 200 V. Typically the input is rectified and converted using a DC/DC.
You can try some of the following:
TDK KWD5-1515
TDK KWD10-1515
Recom RAC10-15DA
I would try some of them or contact the manufacturers regarding DC operation.

Good luck!

Ernest
 
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    sabu31

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Yes, an offline switcher like those meant for 85-265VAC will should work (so long as it doesn't have any PFC or brownout detectors in it), but probably not at his lower range of input voltage. No offline converter is going to work with less than 100VDC on it's input. But if he adjusts his spec to only work with inputs above ~120VDC, then that should work fine.
 

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