LM3886 at very low load < = ohm - Page 2 - diyAudio
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Old 6th December 2012, 07:07 PM   #11
Mooly is online now Mooly  United Kingdom
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This is what my version of the data sheet says,

Supply Voltage |V+| + |V−| 20V to 84V

So thats -/+10 to -/+ 42 volts.
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Old 6th December 2012, 07:53 PM   #12
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There are some TDA7293 kits available on ebay that have 7 parallel TDA7293 chips.
if one chip can drive 4 ohm, 2 chips can drive 2 ohm, 4 chips can drive 1 ohm etc. They are inexpensive.

Assembled DIY Power Audio AMP 7*TDA7293 Parallel 555W Mono HiFi Amplifier Board | eBay
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Old 6th December 2012, 07:55 PM   #13
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Quote:
Originally Posted by AndrewT View Post
+-10V as a minimum, is met by your two 12V car batteries.
But you must ensure that the chipamp does not drop out if the voltage AT THE PINs droops to near 10V. I think one pin has a cut out set to ~ 9V.

I was planning to use a ridiciously large cap bank... Have atleast 50 000 uF per rail.

Worst case I will increase supply voltage a few volts. As I wrote, I have cooling capacity to spare.
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Old 7th December 2012, 12:29 AM   #14
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Well, your real limiting parameter is Peak current capability, which I don't remember now but I guess it should be way over 4 Amps.
TDA20xx and such hover between 3.5A and almost 4.5A
What does the datasheet say?
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Old 7th December 2012, 11:14 AM   #15
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Min 7,5 amps, typical 11 amps so it should be fine.
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Old 7th December 2012, 11:17 AM   #16
AndrewT is online now AndrewT  Scotland
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but only when "cold"
Tc=25degC is specified in the datasheet.

That limit will decrease with increase in chip temperature (Tj).
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Old 7th December 2012, 12:55 PM   #17
Bazukaz is offline Bazukaz  Lithuania
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Hi,

I have been using LM3886 with loads which drop to less < 1 Ohm at certain frequencies. In some cases as low as 0.5 Ohm.
Supply voltage +/- 32V.
The amp is very likely to work normally until the point where the chip is overloaded then SPIKE protection kicks in. That means output voltage is limited.
It will not self destruct normally(although it is doable when you bridge the chips and run at very low load impedance).

Hope this helps,
Lukas.
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Old 7th December 2012, 03:17 PM   #18
AndrewT is online now AndrewT  Scotland
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..................(although it is doable when you bridge the chips and run at very low load impedance)...............
did you mean to type "bridge"?
Or should it show "parallel"?
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