TPA3138D2: PLIM configuration

Fabio Gou

Expert 4575 points

Part Number: TPA3138D2

if the AVDD is 5V, the speaker is 4Ω, Maximum power is 4W.

How can I configurate the PLIMIT Pin?

I did not get it via the datasheet.

Could you give me a calculation example?

over 1 year ago

0 Shadow He over 1 year ago

TI__Guru 55300 points

Hi Fabio

I'm afraid the output power already limited by your AVDD voltage. The output can never higher than your supply, which means 5V as peak voltage. And 5V peak sinewave can only give 3.12W as max on 4ohm load.

0 Fabio Gou over 1 year ago in reply to Shadow He

TI__Expert 4575 points

So how about 14V input voltage, 10W 8Ω speaker；

Could you give a recommending resister configuration in the PLIMIT Pin?

0 Yanming Gong over 1 year ago in reply to Fabio Gou

TI__Mastermind 19860 points

Hi Fabio

The datasheet calculaton is only for unclipped application. PLIMIT function only limit output voltage, not to limit power.

0 Fabio Gou over 1 year ago in reply to Yanming Gong

TI__Expert 4575 points

So in 1SPW mode, the virtual rail is 11.4 times PLIMIT Pin.

If PLIMIT pin voltage is 1V, the speaker is 4Ω.

Then the Plimit= (11.4/1.414)*(11.4/1.414)/4=16.25W.

Is it right?

0 Yanming Gong over 1 year ago in reply to Fabio Gou

TI__Mastermind 19860 points

Hi Fabio

You did not understand what I mean.

If PLIMIT pin voltage is 1V, output peak voltage is 11.4V. But if 11.4V has exceeded PVCC voltage, the output peak voltage can not reach 11.4V! Output can not exceed PVCC.

PLIMIT function only limit output voltage, not to limit power.

0 Fabio Gou over 1 year ago in reply to Yanming Gong

TI__Expert 4575 points

Hi Yanming,

I understand this.

Sorry that I did not mention the working condition.

The customer will use 14V PVCC and 5V PVCC in different model.

So in 14V condition, whether the below calculation is right in 1SPW mode?

Then the Plimit= (11.4/1.414)*(11.4/1.414)/4=16.25W.

+1 Shadow He over 1 year ago in reply to Fabio Gou

TI__Guru 55300 points

Hi Fabio

Yes, that's no problem.

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TPA3138D2: PLIM configuration