Author Topic: Texas Instruments 3116D (ClassD) amp chip  (Read 10482 times)

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Offline DW1961Topic starter

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Texas Instruments 3116D (ClassD) amp chip
« on: August 09, 2020, 09:21:51 pm »
The amp I have uses the TA 3116D chip, and they manufacturer actually makes one with 2 of those chips, and states twice the power.

Amp: https://www.amazon.com/gp/product/B07NY19148/ref=ask_ql_qh_dp_hza
"If you use a full power supply, it is 200W @ 4 ohm, 150W @ 6 ohm, 100W @ 8 ohm."

TA 3116D spec sheet:

https://www.ti.com/lit/ds/symlink/tpa3116d2.pdf?ts=1596921462063&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPA3116D2

"The TPA31xxD2deviceis a highly efficient Class D audio amplifier with integrated 120m Ohms MOSFET that allows output currents up to 7.5 A. . . Wide Voltage Range:4.5 V to 26 V

So how are they getting 200 watts out of two of these at 4 Ohms with a 24-26V driver? (Max is 26V)

« Last Edit: August 09, 2020, 09:23:52 pm by DW1961 »
 

Online magic

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #1 on: August 10, 2020, 06:37:37 am »
There aren't too many ways to combine two power amps. Either in parallel or in series (bridged), depending on whether current or voltage is the limiting factor.
 

Online mikerj

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #2 on: August 10, 2020, 08:44:09 am »
So how are they getting 200 watts out of two of these at 4 Ohms with a 24-26V driver? (Max is 26V)

A combination of paralleling the outputs of two amplifiers to increase drive capability, and by making very optimistic claims (aka lying)

You can't can't bridge the output of these amps as they already a bridged architecture internally.

 

Offline DW1961Topic starter

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #3 on: August 10, 2020, 05:58:10 pm »
So how are they getting 200 watts out of two of these at 4 Ohms with a 24-26V driver? (Max is 26V)

A combination of paralleling the outputs of two amplifiers to increase drive capability, and by making very optimistic claims (aka lying)

You can't can't bridge the output of these amps as they already a bridged architecture internally.

I guess you could use a higher voltage driver and split the voltage across both chips? However, that's not what they are doing. They are using a19V power supply, and they do admit that the 19V power supply will not put out max power specified by the chips. I'm just wondering that using a 19V power supply, even one chip will be lower than the specs state, so how can they power two of them with the same power supply and get more power out of the chips?
 

Offline lutkeveld

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #4 on: August 10, 2020, 07:53:54 pm »
You can get 100W out these chips if you parallel the outputs (PBTL) but then you need a 2 ohm load.
So probably the spec is not completely false, but its: 2x100W at 2 ohm each.
 
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Offline DW1961Topic starter

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #5 on: August 11, 2020, 04:54:48 am »
You can get 100W out these chips if you parallel the outputs (PBTL) but then you need a 2 ohm load.
So probably the spec is not completely false, but its: 2x100W at 2 ohm each.

Yeah that's it.

But what I don't get is why do you need two of these chips?

If you use a 24V driver into 8 Ohms, you get 72 watts at 3 A.

What is the benefit of running two of these when the power stays the same, and one amp chip is capable of putting out the same wattage using the same driver for both chips?
 

Offline lutkeveld

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #6 on: August 11, 2020, 05:43:53 am »
Because now you have 2x100W at 2 ohm instead of 2x50W at 4 ohm :)

You are right that with the same drivers, nothing changes. But you can use different drivers, or put extra drivers in parallel.
And of course it sounds better for marketing :)
 
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Offline DW1961Topic starter

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #7 on: August 11, 2020, 06:45:39 am »
Because now you have 2x100W at 2 ohm instead of 2x50W at 4 ohm :)

You are right that with the same drivers, nothing changes. But you can use different drivers, or put extra drivers in parallel.
And of course it sounds better for marketing :)

So they put two chips in that amp, and use the same power supply, and get nothing from it except marketing hype?
 

Online mikerj

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #8 on: August 11, 2020, 09:02:58 am »
You can get 100W out these chips if you parallel the outputs (PBTL) but then you need a 2 ohm load.
So probably the spec is not completely false, but its: 2x100W at 2 ohm each.

But not using the 25v/3Amp (i.e. 75Watt) power supply that they specify.
 

Offline DW1961Topic starter

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #9 on: August 12, 2020, 01:34:56 am »
You can get 100W out these chips if you parallel the outputs (PBTL) but then you need a 2 ohm load.
So probably the spec is not completely false, but its: 2x100W at 2 ohm each.

But not using the 25v/3Amp (i.e. 75Watt) power supply that they specify.
Here is another one stating the 200 watts, but they do specify 2 ohms. They are using a 24v 4.5 amp driver.
https://www.amazon.com/gp/product/B0887VX6H1

Here are the 3116D specs "100 watts at 2 ohms mono (page 1).
https://www.ti.com/lit/ds/symlink/tpa3116d2.pdf?ts=1596921462063&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPA3116D2

That one is coning to my house free of charge. The last one I got from a different seller on Amazon had some nasty hiss when turned up all the way with no music playing, so I sent it back. I have the single 3116D version now and it's all I need. I remember testing the dual 3116D amp, and I don't know how they are doing it, but it is putting out some serious power. I could really tell because the speakers had a LOT more punch to them.

The max power they are going to get with the 24V driver at 8ohms is 72 watts.

So again, regardless of how many chips they use, they still have a specific amount of power to use. My argument is that if a single 3116D chip will put out the same watts as two of them, given the same power supply, what is the benefit of using two of them?

And, here is it at 8 ohms @ 24V, about 72 watts total. So how dos two of them make more power @ 8 Ohms?



« Last Edit: August 12, 2020, 01:44:29 am by DW1961 »
 

Offline tooki

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #10 on: August 12, 2020, 08:36:10 pm »
How is it not clear to you?!?

That chip can do 100W mono into a 2 ohm load. So they’re using two of them to get stereo.

As for total power, remember that you need the voltage to reach the peaks, but that most of the signal is below the peaks. So the power supply doesn’t need to have quite as much power as you think, since capacitors are used to feed current spikes.
 

Offline DW1961Topic starter

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #11 on: August 15, 2020, 05:22:19 am »
How is it not clear to you?!?

That chip can do 100W mono into a 2 ohm load. So they’re using two of them to get stereo.

As for total power, remember that you need the voltage to reach the peaks, but that most of the signal is below the peaks. So the power supply doesn’t need to have quite as much power as you think, since capacitors are used to feed current spikes.

Hey, sorry about the delay. I'm still interested in this topic. I just had some real life things to deal with.


I had no idea you could run a chip in mono and get stereo out of them by running two of them in mono. Pretty basic stuff, so I apologize for that.

As far as power goes, I'm always talking about continuous power. So if you're running a 24V driver, your max output is going to be 72 watts, right?


I just got this amplifier. It looks like the Chinese are upping their game. It's case is very well made with recessed, high friction  knobs and the volume knob clicks as you turn it. It does have some cheesy screen printing on it--lol.

https://www.amazon.com/gp/product/B0887VX6H1


It uses two Texas Instruments 3116D2 chips (link above) and the TI NE5532 operational amplifier (link below).
https://www.ti.com/lit/ds/symlink/ne5532.pdf

I'm assuming that's an LFE sub output? It says it is an active sub output.
1047570-0<-------Sorry for end of post attachments. I can;t get the inline function to work.
1047570-1<-----------Not working either.


Regardless of power output, I'll bet this thing has some serious punch to it. Makes me want to get a R series Klipsch sub woofer to go with my R-51M Klipsch speakers.



« Last Edit: August 15, 2020, 05:33:08 am by DW1961 »
 

Offline tooki

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #12 on: August 15, 2020, 12:54:26 pm »

Hey, sorry about the delay. I'm still interested in this topic. I just had some real life things to deal with.
No worries, it happens to all of us!

I had no idea you could run a chip in mono and get stereo out of them by running two of them in mono. Pretty basic stuff, so I apologize for that.
The channels of an audio chain are fundamentally separate. We just control them in (usually) pairs for convenience.

Class D amplifiers are a bit of an exception, in that many of them take advantage of the fact that they actually have way more power available than they need, letting them actually alternate powering the two channels, reducing the instantaneous current draw. (This is why you must only bridge class D outputs in the ways listed in the datasheet.)

As far as power goes, I'm always talking about continuous power. So if you're running a 24V driver, your max output is going to be 72 watts, right?
Nope. You’re going by the math for DC, but it’s not DC, it’s AC.

Some things to understand:
1. The supply voltage is what limits the maximum power of the amp, as it is the highest voltage that be present on the output. For any given speaker impedance, it is the maximum voltage alone that limits the power. But it’s a sine wave, so the vast majority of the signal is below the peak voltage.

2. Many (most?) class D amps, including the one here, use creative switching to produce both the positive and negative sides of the output waveform from a single-polarity power supply (let’s call this VCC). This means that the output voltage can swing from +VCC to -VCC, meaning a peak-to-peak voltage of VCCx2. So if your VCC is 24V, then your output can swing from +24 to -24 volts, a total peak-to-peak voltage of 48V!

3. In a sine wave, the peak voltage is only reached for a tiny amount of time. Most of the time is less. So we measure using RMS, the value of the AC signal given as the DC voltage with the equivalent heating power. For a pure sine wave, the RMS value is the square root of 2 (about 0.707) times the peak voltage (which in an amp is at most the VCC). So for your 24V VCC, the RMS becomes 24x0.707, or about 17V. And that gives you a maximum average power of 36W into 8 ohms (a current draw of 2.125A). (You can also calculate it as VCC2/2x(impedance).)

4. Music isn’t a singular, always-full-amplitude sine wave. That’d just be a single loud tone. Nor is music multiple sine waves of different frequencies, but always full amplitude. No, it’s nearly infinitely many simultaneous sine waves of different frequencies at highly varying amplitudes. Indeed, most of them will be far below the peak amplitude (since the peak is necessarily the peak sum of all the frequencies at any instant). The consequence of this is that the average power is far lower than the peak power, easily a factor of half at full volume.

5. As such, while you will need capacitors to ensure the peak current can be supplied, the power supply only needs to be beefy enough to supply the average current. That’s why you can get away with the small power supplies commonly used in audio gear now.

And that’s all assuming you’re running it at full blast. At typical home, indoor listening levels, you don’t need but a tiny fraction the power. One of the 3116’s at just 7 volts into 8 ohm speakers is enough to be much too loud to have a conversation, and that’s just 3 watts per channel max. Nighttime watching a TV show, for instance, will have the 3116 drawing maybe 30mA at 5 volts, so 150mW total (and at 5V, the 3116’s quiescent current with no signal is about 15mA, so at most 75mW actually going to the speakers!).

A lot of info, but I hope it helps. Of course there are lots of other things that come into play and slightly increase the power needed, but this should help understand why you can’t just apply ohms law to the supply voltage to calculate an amp’s power.
 

Offline DW1961Topic starter

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #13 on: August 15, 2020, 05:12:44 pm »

Hey, sorry about the delay. I'm still interested in this topic. I just had some real life things to deal with.
No worries, it happens to all of us!

I had no idea you could run a chip in mono and get stereo out of them by running two of them in mono. Pretty basic stuff, so I apologize for that.
The channels of an audio chain are fundamentally separate. We just control them in (usually) pairs for convenience.

Class D amplifiers are a bit of an exception, in that many of them take advantage of the fact that they actually have way more power available than they need, letting them actually alternate powering the two channels, reducing the instantaneous current draw. (This is why you must only bridge class D outputs in the ways listed in the datasheet.)

As far as power goes, I'm always talking about continuous power. So if you're running a 24V driver, your max output is going to be 72 watts, right?
Nope. You’re going by the math for DC, but it’s not DC, it’s AC.

Some things to understand:
1. The supply voltage is what limits the maximum power of the amp, as it is the highest voltage that be present on the output. For any given speaker impedance, it is the maximum voltage alone that limits the power. But it’s a sine wave, so the vast majority of the signal is below the peak voltage.

2. Many (most?) class D amps, including the one here, use creative switching to produce both the positive and negative sides of the output waveform from a single-polarity power supply (let’s call this VCC). This means that the output voltage can swing from +VCC to -VCC, meaning a peak-to-peak voltage of VCCx2. So if your VCC is 24V, then your output can swing from +24 to -24 volts, a total peak-to-peak voltage of 48V!

3. In a sine wave, the peak voltage is only reached for a tiny amount of time. Most of the time is less. So we measure using RMS, the value of the AC signal given as the DC voltage with the equivalent heating power. For a pure sine wave, the RMS value is the square root of 2 (about 0.707) times the peak voltage (which in an amp is at most the VCC). So for your 24V VCC, the RMS becomes 24x0.707, or about 17V. And that gives you a maximum average power of 36W into 8 ohms (a current draw of 2.125A). (You can also calculate it as VCC2/2x(impedance).)

4. Music isn’t a singular, always-full-amplitude sine wave. That’d just be a single loud tone. Nor is music multiple sine waves of different frequencies, but always full amplitude. No, it’s nearly infinitely many simultaneous sine waves of different frequencies at highly varying amplitudes. Indeed, most of them will be far below the peak amplitude (since the peak is necessarily the peak sum of all the frequencies at any instant). The consequence of this is that the average power is far lower than the peak power, easily a factor of half at full volume.

5. As such, while you will need capacitors to ensure the peak current can be supplied, the power supply only needs to be beefy enough to supply the average current. That’s why you can get away with the small power supplies commonly used in audio gear now.

And that’s all assuming you’re running it at full blast. At typical home, indoor listening levels, you don’t need but a tiny fraction the power. One of the 3116’s at just 7 volts into 8 ohm speakers is enough to be much too loud to have a conversation, and that’s just 3 watts per channel max. Nighttime watching a TV show, for instance, will have the 3116 drawing maybe 30mA at 5 volts, so 150mW total (and at 5V, the 3116’s quiescent current with no signal is about 15mA, so at most 75mW actually going to the speakers!).

A lot of info, but I hope it helps. Of course there are lots of other things that come into play and slightly increase the power needed, but this should help understand why you can’t just apply ohms law to the supply voltage to calculate an amp’s power.

Yes, understood. I read a lot about how RMS is calculated and it's the avg of the sine wave and so on.

In another thread on the same subject I posted that using the volume knob with my Klipsch R-51M speakers (93dB sensitivity), I can not get it over about half way, which if it is at all accurate is giving the speakers about 11 watts each. It's just glaringly loud at that point. (That's with a 19V power supply.)

I went to the Amazon page and asked the seller what the continuous output was at 8 ohms using their 24V power supply:

Q: The 3116D chip is only rated 100w @ 2ohms mono. Using the included power supply, what is total power output @ 8 Ohms?
A: when you use 8ohm speaker, the total power is 35-50W.

I should have asked what the continuous power is, but what he said was accurate given the oms to watts calculations, which would be 35-36 watts continuous. I think he means 35 watts continuous and 50 peak.

Back to my question, though:

So, my question, again, what is the benefit of using two 3116D chips when you  get the same power output as one chip at 8 ohms?
 

Offline DW1961Topic starter

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #14 on: August 15, 2020, 05:25:58 pm »
Just wanted to say that the amp I posted here is not a powered sub out. It requires an active subwoofer--which is good. That leaves all power for the mids and tweets. Damn, I'll bet this thing with a 10" Klipsch active sub and the R-51M speakers as mids and highs would be incredible.
 

Offline TimFox

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #15 on: August 15, 2020, 09:18:44 pm »
Turning the volume control to 12 o’clock does not mean you are putting out half power.
Look at my earlier response to one of your many posts about estimating your power output and requirements using a CD player.
 

Offline DW1961Topic starter

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #16 on: August 15, 2020, 11:04:39 pm »
Turning the volume control to 12 o’clock does not mean you are putting out half power.
Look at my earlier response to one of your many posts about estimating your power output and requirements using a CD player.

I understand that for sure. The point I was making is that the knob is never past a 25-35% when I first hear music. And, that is nowhere near full power because it will continue to get louder all the way to the right stop, when the dial no longer turns. I don't know how many watts it is, but it is nowhere near 50%.

As far as testing how many watts are being used at a specific dial indication, wouldn't it be easier to use a MM connected to the amps outputs for volts and a clamp meter to get amps?
 

Offline TimFox

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #17 on: August 15, 2020, 11:37:07 pm »
Again, I refer you to my other post.  To determine the output power under continuous conditions, you measure the voltage into a known resistance R and calculate P = V2/R.
The volume control is a log-taper gain control.  The output power also depends on the input level.
A typical gain control might have a useful range of 40 dB, so half way would be 20 dB below the maximum gain.  However, with a “normal” source signal level, the maximum gain may be way too much for the output capability of the amplifier.  My good preamp uses a precision stepped-switch attenuator, where the output is shorted at full CCW, with 48 steps.  At top center, the attenuation is 24 dB.
« Last Edit: August 16, 2020, 05:14:18 pm by TimFox »
 

Offline tooki

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #18 on: August 16, 2020, 02:37:12 pm »

So, my question, again, what is the benefit of using two 3116D chips when you  get the same power output as one chip at 8 ohms?
I don’t think there is one, since with the 8 ohm speakers, you’re hitting the voltage limits before you hit current limits.
 
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Offline TimFox

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #19 on: August 16, 2020, 05:13:25 pm »
The conflict between voltage and current limits is why vacuum tube amps use transformers with secondary taps for different load impedance, to get the same power output at different loads.  From the tube’s “characteristic curves” one can determine the higher impedance load line (at the plates) that satisfies the voltage and current limits without exceeding the plate dissipation power.
 
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Offline DW1961Topic starter

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #20 on: August 16, 2020, 06:08:08 pm »
[ Specified attachment is not available ]
The conflict between voltage and current limits is why vacuum tube amps use transformers with secondary taps for different load impedance, to get the same power output at different loads.  From the tube’s “characteristic curves” one can determine the higher impedance load line (at the plates) that satisfies the voltage and current limits without exceeding the plate dissipation power.

Here is something. According to this calculator, you're never ging to get 200 watts out of that amp, not continuous. As Tim has said, sure, with caps and for brief burst, but nowhere near 200 watts continuous. That is, unless the calculator is not taking into consideration other amp related/audio related parameters:

Most importantly, the power supply is 24V and 5 Amps. Anyway, I have no idea, again, why they would use two chips with a 24v/5A driver. There must be some reason, at least that's what my head is telling me. In fact, at 2 Ohms, in order to not exceed the driver's 5 Amp max, you get 50 watts total because the voltage drops to 10V. In order to get 200 watts total, you would have to go to 10 Amps/ 20V. (All according to the calculator).

The images are suppose to display inline full size, so if they are not, no idea. All options default to end of post thumbnails.





« Last Edit: August 16, 2020, 06:14:46 pm by DW1961 »
 

Offline tooki

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #21 on: August 16, 2020, 07:41:17 pm »
You still don’t understand the practical significance of the whole RMS vs peak voltage thing I laid out for you in detail.
 

Offline DW1961Topic starter

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #22 on: August 16, 2020, 08:23:37 pm »
You still don’t understand the practical significance of the whole RMS vs peak voltage thing I laid out for you in detail.

Gonna go back and read that again. 
 

Offline DW1961Topic starter

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #23 on: August 17, 2020, 12:02:20 am »


3. In a sine wave, the peak voltage is only reached for a tiny amount of time. Most of the time is less. So we measure using RMS, the value of the AC signal given as the DC voltage with the equivalent heating power. For a pure sine wave, the RMS value is the square root of 2 (about 0.707) times the peak voltage (which in an amp is at most the VCC). So for your 24V VCC, the RMS becomes 24x0.707, or about 17V. And that gives you a maximum average power of 36W into 8 ohms (a current draw of 2.125A). (You can also calculate it as VCC2/2x(impedance).)


Ok, so I see how you get peak power from a 24V power supply. I did it like this, becasue the rated power on the supply is 24V RMS:

So:
24/.707 = 34V
and
34*.707=24.7V

Yes, they are talking about "max" power output, so sure, you can get 200 watts out of a 24V RMS power supply rated at 5A.

Back to my original problem, I'm not seeing how you get anymore than 100 watts continuous power at 4 Ohms using that 24V/5A power supply.

I think some of my problem is that I don't see where contious power or peak power is stated int eh Texeas Instruments spec file:

The chips are rated at peak power of x2 50  watts at 4 Ohms. (Peak, Continuous?)
Top of document:
https://www.ti.com/lit/ds/symlink/tpa3116d2.pdf?ts=1596921462063&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPA3116D2

Each 3116D chip is rated for a continuous power of  50 watts @ 21V and 4 Ohms. (Total or x2?)
Section 6.6AC Electrical Characteristics (Same document)

If the continuous power spec means 50 watts total at 4 Ohms @ 21V, then ok:

So you can get 100 watts @ 20V and 5A and 4 Ohms from a 24V/5A continuous power supply.

So using two 3116D chips, you can get double the power, then, at 4 Ohms. (two chips at 2 Ohms bridged = 4 Ohms.)

How am I doing?
 

Online rsjsouza

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Re: Texas Instruments 3116D (ClassD) amp chip
« Reply #24 on: August 17, 2020, 01:06:31 am »

Yes, they are talking about "max" power output, so sure, you can get 200 watts out of a 24V RMS power supply rated at 5A.

Back to my original problem, I'm not seeing how you get anymore than 100 watts continuous power at 4 Ohms using that 24V/5A power supply.

I think some of my problem is that I don't see where contious power or peak power is stated int eh Texeas Instruments spec file:
Table at section 6.6 of the datasheet indicates 50W continuous at 4 ohms with 21Vcc.  According to the description, this is per channel - in BTL it will do 100W under the same conditions. A side note: keep in mind this is under 10% of signal distortion - far from a hi-fi under these conditions (it will have less distortion if driven at lower power).

So you can get 100 watts @ 20V and 5A and 4 Ohms from a 24V/5A continuous power supply.
The output power equals the supply power minus losses - in other words, the efficiency of the circuit. 24V/5A will give you 120W of supply, which may be just enough for continuous operation of 100W total or 50W per channel - the efficiency is shown at figure 23 of the datasheet.

Higher peak power may or may not be attained. Section 7 describes the drivers will pull up to 7.5A at peak conditions (which gives a 200W peak under 4 ohms).
« Last Edit: August 17, 2020, 01:30:36 am by rsjsouza »
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Oh, the "whys" of the datasheets... The information is there not to be an axiomatic truth, but instead each speck of data must be slowly inhaled while carefully performing a deep search inside oneself to find the true metaphysical sense...
 
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