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Old 1st August 2012, 05:28 AM   #11
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I bought a dual output isolated dc to dc converter from Murata. It has -12 and +12 output.

When i hook it up to power it shows the right output but when I plug it into my amp it drops to -1.2v & +1.2 and will not work.

If I use my other +12v source and the -12v source from the Murata it works but if I use both the +12 and the -12v from the Murata it will not work.

Any ideas?

in the data sheet for the DC to DC converter it says teh common is floated but I tried with nothing connected to the common and that didnt work either.

Mike
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Old 1st August 2012, 08:27 AM   #12
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What are the amp's 12 volt power requirements, and are they met by the DC-DC converter?
The ICEpower datasheet gives a quiescent current of +12V @ 70mA and -12V @ 20mA. So if the DC-DC converter can only supply, for example, 50mA through each half...
I can easily imagine the results you're seeing.

edit: BTW, the floating ground on the converter output means it has no reference to the either the + or - of the 12V input voltage.
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Last edited by sofaspud; 1st August 2012 at 08:31 AM.
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Old 1st August 2012, 10:15 AM   #13
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What is the model of the converter? Some of these have input/output capacitor requirements and some even have "sense" pins that also need to be connected for proper regulation.
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Old 2nd August 2012, 07:29 AM   #14
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This is the dc to dc that I am using.

It's a 3 watt ps and I am drawing about 1watt.

This seems like it should work but it's not???

Mike

BWR-12/125-D48-C | Bipolar Output Isolated | DC-DC Converters | Products | Murata Power Solutions
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Old 2nd August 2012, 07:42 AM   #15
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I hope I'm not the bearer of bad news... that converter page shows a "Input Voltage Range (V) 18 to 72" with a nominal input of 48V. Not 12V.
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Old 2nd August 2012, 08:40 AM   #16
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He mentioned earlier he's using a 48V supply.
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Old 2nd August 2012, 09:00 AM   #17
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Ah, thanks, that keeps my hopes up.
I'd have to defer to the previous suggestion concerning cap requirements. How does the datasheet circuit compare with the one in actual use (including the ICEpower side)? Murata claims that in/out caps aren't strictly necessary, but there may be something with this particular app that makes it/them especially necessary. I've used this same converter series with no problems.
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Old 2nd August 2012, 04:06 PM   #18
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Yes I am using a 48v source.

When I measure on the bench it is fine. so I know its working right and I must be doing something wrong in the way I am hooking up to the load.

I am sure I am missing something simple. Although it seems like there are not many variables.

My only concern is that the converter says to float the output common as in leave it open. That seems odd.

I wonder if I use the amp ground on the input of the DC to DC converter instead of the battery ground. that might make a difference.

Mike
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Old 2nd August 2012, 07:06 PM   #19
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The connections should look like this....
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Old 2nd August 2012, 08:53 PM   #20
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Quote:
Originally Posted by theAnonymous1 View Post
The connections should look like this....
Yes that is how I hooked it up and it was not working.

Glad I was not doing it wrong but I dont get why it's not working.

Mike
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