LM3886 overvoltage

xplod1236 · 20th July 2004, 12:22 AM

What will happen if I apply too much voltage to the LM3886?
The max voltage for the chip is +/- 42, so what will happen if I feed it 45v?

mrrao · 20th July 2004, 01:06 AM

not guaranteed Outgoing Quality Level .
propositional supply voltage under +/-42V

Jay · 20th July 2004, 02:29 AM

Although there is a bit inconsistency in the pdf, it is
shown in the summary page that LM3886 features a wide
operating voltage up to 94V, which is +/-47V with split
power supply. Although there is no condition specified
I think good manufacturers should employ a safety factor
in the specs.

I'm not anywhere near afraid to feed mine with 45V, and
I don't think it will be blown up. The conditions are:

1) I employ a good practice in sinking the chip to the
heatsink. If the heatsink is hot, then make it biger.

2) My speakers are 2-way and cannot withstand too much
power anyway (about 50W average). Never measured the
speaker but I guess it won't go below 3 Ohm.

About heatsinking, it is very crucial. A trapped air due
to uneven surface may lead to the chip withstanding heat
it doesn't supposed to. IMHO, the chip failure must be
started with (slow) overheating, except when oscillate.

xplod1236 · 20th July 2004, 03:08 AM

So if I keep the chips cool, it will be good?

I once ran the chip on +/- 50v rails, and it worked. Then, for some reason I don't remember, I disconnected the signal while the amp was on. When I went to connect the signal again, I don't remember exacly, but I got a spark from the signal plug to the jack. That went to the chip and fried it.

20th July 2004, 12:22 AM	#1
xplod1236 diyAudio Member Join Date: Dec 2003 Location: On the couch	LM3886 overvoltage What will happen if I apply too much voltage to the LM3886? The max voltage for the chip is +/- 42, so what will happen if I feed it 45v?

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20th July 2004, 01:06 AM	#2
mrrao diyAudio Member Join Date: Jul 2004 Location: shenzhen city	not guaranteed Outgoing Quality Level . propositional supply voltage under +/-42V

20th July 2004, 02:29 AM	#3
Jay diyAudio Member Join Date: Feb 2003 Location: Jakarta	Although there is a bit inconsistency in the pdf, it is shown in the summary page that LM3886 features a wide operating voltage up to 94V, which is +/-47V with split power supply. Although there is no condition specified I think good manufacturers should employ a safety factor in the specs. I'm not anywhere near afraid to feed mine with 45V, and I don't think it will be blown up. The conditions are: 1) I employ a good practice in sinking the chip to the heatsink. If the heatsink is hot, then make it biger. 2) My speakers are 2-way and cannot withstand too much power anyway (about 50W average). Never measured the speaker but I guess it won't go below 3 Ohm. About heatsinking, it is very crucial. A trapped air due to uneven surface may lead to the chip withstanding heat it doesn't supposed to. IMHO, the chip failure must be started with (slow) overheating, except when oscillate.

20th July 2004, 03:08 AM	#4
xplod1236 diyAudio Member Join Date: Dec 2003 Location: On the couch	So if I keep the chips cool, it will be good? I once ran the chip on +/- 50v rails, and it worked. Then, for some reason I don't remember, I disconnected the signal while the amp was on. When I went to connect the signal again, I don't remember exacly, but I got a spark from the signal plug to the jack. That went to the chip and fried it.

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