TPA3116 amplifier power

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dfy

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Joined 2013
The TPA3116 chip actually works with voltages down to 5V. This particular board may or may not, but for a price as low as that I would definitely try it.

Take into account though that even if it works, you will get nowhere near the 50W+50W power claimed on a 12V supply.
 
R

roubi

Member
Joined 2011
Thanks for the answers.
Indeed, the parameters say that it needs 18V at least, but very often, the specification are not that right on Aliexpress.
I will definitely try it if nobody did it yet.

And I am aware that I won't get 50+50W with 12V, but I need less than that.
Thanks a lot !
 
xrk971

xrk971

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roubi said:
Thanks for the answers.
Indeed, the parameters say that it needs 18V at least, but very often, the specification are not that right on Aliexpress.
I will definitely try it if nobody did it yet.

And I am aware that I won't get 50+50W with 12V, but I need less than that.
Thanks a lot !
Click to expand...

If you look at the parameters as specified by the manufacturer, only 4.5 volts is needed and max is 26 volts.

http://www.ti.com/lit/ds/symlink/tpa3118d2.pdf
 
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KJA 2013

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macster

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Joined 2015
Saturnus said:
You don't need a chart. You need Ohm's Law:

W(RMS) = V^2/(2Z)

Where V=supply voltage and Z=load impedance
Click to expand...

Thanks for the insight. I found an Ohms Law Calculator that really seems to help:
Ohm's Law Calculator

So if I got this right: 12 volt with 4 Ohm Speakers = 36 Watts Total Power @ 3000 MAh? So for 2 speakers that would be 18 Watts each and 3 hours runtime on a 9000 Mah battery at max?
 
Saturnus

Saturnus

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Joined 2005
macster said:
Thanks for the insight. I found an Ohms Law Calculator that really seems to help:
Ohm's Law Calculator

So if I got this right: 12 volt with 4 Ohm Speakers = 36 Watts Total Power @ 3000 MAh? So for 2 speakers that would be 18 Watts each and 3 hours runtime on a 9000 Mah battery at max?
Click to expand...

Well. Not exactly. It's (12*12)/(2*4) = 18W per channel. That's at ridiculously high THD though (serious clipping) so typically you say 80% to get a reasonably realistic number. So about 14.4W per channel.

Now you'd think that would mean power consumption is 28.8W stereo but it's not. Music has a crest factor, ie. average is far lower peak, and even RMS. Typically you divide the 28.8W with 10 so that average is 10% of RMS.

But that 2.88W is still not the full story because now you have to find the amplifiers efficiency at 10% which is significantly lower than the maximum efficiency. For TPA3116 it's about 80% efficiency at 2.88W into 4 ohm at 12V supply voltage so that brings the power consumption for the output stage to 3.6W or 300mA. To that you just add the quiescent current of 20mA at 12V supply voltage.

So all in all average power consumption is 320mA with 12V supply voltage playing stereo music signals at full power before seriously audible clipping.
 
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lutkeveld

Member
Joined 2013
Macster, the calculator assumes you're using DC, but you're using AC (audio). The RMS value of an AC signal is 1/sqrt(2) below peak. So what you get instead of P=U^2/R is P=(U*1/sqrt(2))^2/R, which is the same as P=U^2/2R.

So as Saturnus said, max theoretical output per channel at 12v is 18W.
 
M

macster

Member
Joined 2015
lutkeveld said:
Macster, the calculator probably assumes you're using DC, but you're using AC (audio). The RMS value of an AC signal is 1/sqrt(2) below peak. So what you get instead of P=U^2/R is P=(U*1/sqrt(2))^2/R, which is the same as P=U^2/2R.

So as Saturnus said, max theoretical output per channel at 12v is 18W.
Click to expand...

Man you guys are super smart... I'm trying to get these calculations but it's just WAY over my head. I'm going to keep going back at try to understand a little better.

So, pretty much no matter which amp board you use regardless of wattage, you will not be able to put out more or less than 18w RMS x 2 with 12 volts AC? Sorry, I'm really trying to follow.
 
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lutkeveld

Member
Joined 2013
With 12v in, you can't get more than 12v out. Any amp that claims to do so is lying or is boosting the incoming voltage (like car amplifiers).

Since you want to know how many watts RMS your amp can put out you have to take the RMS value of the signal (peak*1/sqrt(2)) as explained in my previous post.
 
D

dhutch

Member
Joined 2004
spurstow.com/daniel
JonSnell Electronic said:
It states that it requires at least 18volts. Sorry
Parameters
- Way of working: D class Static electricity: 50 ma
- Work efficiency: 90%
- The rated output power: 2 * 50 w
- Frequency response: 20 hz to 20 KHZ
- Operating voltage: DC18V to DC24V
- The maximum output current: 2 A
- PCB unit size: 81 * 69 mm
Click to expand...
dfy said:
The TPA3116 chip actually works with voltages down to 5V. This particular board may or may not, but for a price as low as that I would definitely try it.
Click to expand...

On the flipside, how resistant to over volting would unit be, say if you tried to run it of 28v (24v battery on charge from an alternator) would that fry it?


Daniel
 
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