LM4781 power supply

sancte · 30th June 2006, 01:58 PM

Hi everybody, i'm designing a project with 2 LM4781, +-25 V, that means 6 independent channels of 25~30W.
What about the power supply?The datasheet does not specify anything about the input current per channel.
Thanks in advance.

Santiago.

SpittinLLama · 30th June 2006, 04:42 PM

Depends on if you want that 25-30W per channel to be possible with all 6 channels driving full power at the same time. Then you would need enough current for about 2A per channel or 12A. But it all depends on what you want and how much you want to spend on the power supply. You can also do something like 2 power supplies and have the channels that require the most power on different supplies since some channels, like rear surround channels aren't quite as demanding. But then you need to be sure your GND'ing is all well done. As long as you use a good star GND and don't create loops you shouldn't have any 60Hz hum.

-SL

DJ Exprice · 1st July 2006, 01:09 AM

You always want to have a little left-over amperage too. Use my Bleeder Resistor Switch or just a normal bleeder resistor. If it's a normal bleeder resistor, make sure it's not too low in ohms and not too high

.

30th June 2006, 01:58 PM	#1
sancte diyAudio Member Join Date: Jun 2006	LM4781 power supply Hi everybody, i'm designing a project with 2 LM4781, +-25 V, that means 6 independent channels of 25~30W. What about the power supply?The datasheet does not specify anything about the input current per channel. Thanks in advance. Santiago.

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30th June 2006, 04:42 PM	#2
SpittinLLama diyAudio Member Join Date: Apr 2005 Location: In the Wild, Wild West	Depends on if you want that 25-30W per channel to be possible with all 6 channels driving full power at the same time. Then you would need enough current for about 2A per channel or 12A. But it all depends on what you want and how much you want to spend on the power supply. You can also do something like 2 power supplies and have the channels that require the most power on different supplies since some channels, like rear surround channels aren't quite as demanding. But then you need to be sure your GND'ing is all well done. As long as you use a good star GND and don't create loops you shouldn't have any 60Hz hum. -SL

1st July 2006, 01:09 AM	#3
DJ Exprice diyAudio Member Join Date: Mar 2006 Location: San Francisco, California	You always want to have a little left-over amperage too. Use my Bleeder Resistor Switch or just a normal bleeder resistor. If it's a normal bleeder resistor, make sure it's not too low in ohms and not too high .

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