amplifier with 12v supply
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 Chip Amps Amplifiers based on integrated circuits

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 12th March 2013, 09:33 AM #21 Arvis diyAudio Member   Join Date: Jul 2012 TDA1562, I measured nominal power of 41W @ 14V power supply (would probably be a bit less at 12V), just need to use different capacitors than in most circuits on the internet.
AndrewT
R.I.P.

Join Date: Jul 2004
Location: Scottish Borders
Quote:
 Originally Posted by Arvis TDA1562, I measured nominal power of 41W @ 14V power supply......
Prove it.
__________________
regards Andrew T.

ChristianThomas
diyAudio Member

Join Date: Feb 2006
Location: On a hill, in a wooden shack, next to the woods, in Somerset.
Quote:
 Originally Posted by JMFahey
I don't know your specific objection to what I said, but I don't like power outputs quoted against distortion. The figure we really want is for unclipped power and the distortion figure above that is largely a function of how much of the sine wave has been sliced off.

Quote:
 Originally Posted by JMFahey but that won't turn a 20W amplifier into a 40W one. Gains will be modest.
I thought we were trying to find out if we could get 15W using a 12V battery.

Let's do it the other way around. Power = V^2/R and to get 15W from 4 ohms the RMS voltage will be sqrt(60) = 7.746V. Times sqrt(2) for the peaks = 10.95V, or 22V peak to peak. With a bridged amp we have nominally 24V available, so I reckon that is pretty much doable. With a standard output stage we will have to rely on the battery charging to higher than nominal, but for something modern with a charge pump boosting the driver voltages I would have thought it's eminently possible. Whether the losses are quite this low at full current I haven't looked, but I'd be surprised if there weren't something close among TI's offerings.

Then, of course, there is always the possibility of boosting the supply voltage for the whole thing and you can have any power you want. Hence 500W automotive systems ...

ChristianThomas
diyAudio Member

Join Date: Feb 2006
Location: On a hill, in a wooden shack, next to the woods, in Somerset.
Quote:
 Originally Posted by AndrewT Prove it.
I don't think he needs to.

http://www.nxp.com/documents/data_sh...562Q_ST_SD.pdf

Go to page 13, third line down.

 12th March 2013, 02:36 PM #25 AndrewT   R.I.P.   Join Date: Jul 2004 Location: Scottish Borders Does "lift supply" shown twice tell you or us that 14.4V is NOT the amplifier supply voltage? __________________ regards Andrew T.
 12th March 2013, 02:59 PM #26 johnr66   diyAudio Member   Join Date: Mar 2009 I'm under the assumption that the lift supply in the TDA1562 can only raise the rails temporarily for transients requiring more power. If a continuous waveform is applied, the lift supply is not able to sustain the higher voltage. I could be wrong. My method to determine amplifier power is to measure the power at just before clipping using a continuous sine wave into a non inductive load resistance. If the amplifier has more than one channel, all channels must be driven and loaded. If the lift supply cannot maintain the higher voltage, it cannot maintain the higher output in a proper amplifier power measurement. Last edited by johnr66; 12th March 2013 at 03:02 PM.
 12th March 2013, 08:00 PM #27 Arty diyAudio Member   Join Date: Feb 2011 surely will not qork with a sqare wave, and the lift capacitrs must be high quality. most probably the limiting factor would be the RC time. on the otherhand with audio signals i do not see why should it not work properly. someone has put quite some effort to pack a full class H amp in a chip. i would think this effort did not go to waste. Supposedly the lift capacitors can charge while the output signal is achieveable with the normal supply rails and the caps only kick when the rail is not high enough for the output signal. so supposedly, at least what i think, the caps have time to charge. question is if the powersupply rail will handle the extra load
 13th March 2013, 10:02 AM #28 ChristianThomas   diyAudio Member   Join Date: Feb 2006 Location: On a hill, in a wooden shack, next to the woods, in Somerset. I don't see any reason why it shouldn't work continuously at that power and would imagine that, like most of us (and JohnR66), they define power output as continuous at a given frequency. The size of the capacitor at 4700uF would also seem to point to this. (Besides I don't think you would want to try to sell an amp that collapsed after a few seconds of being pushed hard.) Nor do I see any reason for it not to work with a square wave since all that is happening is that the rails move up in voltage. It's just a question of efficiency and keeping the chip cool or the heatsink size down (in this case down to something practically achievable). The price you pay is an extra pair of caps. It can otherwise be thought of as just an amp with an on-board DC-DC converter (which will be perfectly able to deliver the current needs)
 13th March 2013, 12:32 PM #29 Arty diyAudio Member   Join Date: Feb 2011 I think efficiency is rather good, as its a class H chip.
 13th March 2013, 07:30 PM #30 yoosefheidari diyAudio Member   Join Date: Mar 2013 ok how can i have a 13/0/-13 power supply from a 13v battery? with 0/5A current in +13 and 0/5A in -13 .

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