This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

# TPA3111D1: 5W instead of 10W output power

Part Number: TPA3111D1

Hello

We are using TPA3111D1, but we don´t get 10 watts on the output. Nevertheless, the datasheet say "10-W into an 8-Ω Load at 10% THD+N From a 12-V Supply"

The maximum power we get are 5 watts.

In the input we have a sinusoidal signal of 1kHz / 680mVrms

If we raise the signal level at the input, the output signal is deformed.

We have set the gain in 20dB and we are using a resistor of 8Ω as a load.

The power supply is 12Vdc.

We have the PLIMIT input connected to the GVDD output in order to avoid power limitation.

You can see below our schematic

thanks

Antonio

• Antonio,

Could you describe the reason for D35 and D36?

Could you show us the deformed output?

Is your power supply rated to supply enough current for the system?

Regards,

• Hi Antonio,
I didn't find obvious issue in the SCH. As Adam mentioned, could you please show us the defromed waveform? With PVCC=12C/Load=8Ohm/Pout=10W, the THD is less than 10%. So in this case, it's expected that the output is clipped(but THD is less than 10%). Please refer to the Figure 4, the THD reach around 7~8% with outputing 10W power on 8Ohm load under 12V power supply in the figure. For the Figure, you could see that the THD starts to rise from around 8W~9W output power because of the PVCC clipping. So if you want higher unclipped output power, please use higher PVCC voltage.
Best regards,
Shawn Zheng
• Or lower resistance speaker.
• Hello

D35 and D36 protect the chip against overvoltage (surges) coupled to the cables that connect to the 8 ohms load (loudspeaker). We tried to remove but operation is the same.

We use a laboratory PSU limited to 3A. Nevertheless current is always bellow 0,4A.

thanks

Antonio

• Hi Antonio,
Could you show us the output waveform on the speaker with 10W output power?
•

File1:

Power supply: 12Vdc

Gain: 20dB

Vin: 1KHz / 680mVrms

M à Channel 1 – Channel 2

Channel 1 à OUTN

Channel 2 à OUTP

File2:

Power supply: 12Vdc

Gain: 20dB

Vin: 1KHz / 800mVrms

M à Channel 1 – Channel 2

Channel 1 à OUTN

Channel 2 à OUTP

File3:

Power supply: 12Vdc

Gain: 20dB

Vin: 1KHz / 1Vrms

M à Channel 1 – Channel 2

Channel 4 à Vin

• Hi Antonio,
I think your measurement is expected. The clip is casued by the low power supply voltage, but not the device itself.
You can use higher PVCC voltage power supply or lower resistance load to achieve a higher unclipped output power.
Best regards,
Shawn Zheng
• Hello

attached 3 files:

File1:

Power supply: 12Vdc

Gain: 20dB

Vin: 1KHz / 680mVrms

M  Channel 1 – Channel 2

Channel 1 -- >  OUTN

Channel 2 -- >  OUTP

File2:

Power supply: 12Vdc

Gain: 20dB

Vin: 1KHz / 800mVrms

M -- > Channel 1 – Channel 2

Channel 1 -- > OUTN

Channel 2 -- >OUTP

File3:

Power supply: 12Vdc

Gain: 20dB

Vin: 1KHz / 1Vrms

M -- >Channel 1 – Channel 2

Channel 4 -- >Vin

Input signal is no distorted above 675mVrms but you can see the output figures that are quite deformed.

Antonio

• Hi Antonio,
Did you try with a higher voltage power supply(e.g. 18V or 24V)? Or did you try with 4Ohm speaker? WIth the same output power(10W), there should be no clip on the output.
Best regards,
Shawn Zheng
• Hi Shawn

thanks

The issue is according to datasheet and the conditions we are testing, we should get 10W (with no distortion) and not 5W. Why TI is claiming in the datasheet that this device outputs 10w instead of 5w?

Antonio

• Hi Antonio,

I don't think there is any problem in the datasheet. As I mentioned before, when the device output 10w on 8ohm load with 12V PVCC, the THD is around but less than 10%. The clipping on the output signal is actually caused by the low power supply and high load resistance, but not the device itself. Please be noted that the THD is around 10% in this case, you could find this info in the datasheet.

Best regards,

Shawn Zheng