TPA3250: Analog input range

Cedrick

Part Number: TPA3250

Hi,

Good day. I hope you are doing fine.

Our customer wants to use the TPA3250 however they want a clarification on the analog input voltage range. On page 5 of the TPA3250 datasheet says the Absolute Maximum Range for Analog pins (INPUTX to GND) is -0.3V to 7V. Page 7 says the Analog input voltage swing is 7V.

However, the application schematic (figure 22) shows that the analog inputs are (INPUT_A - INPUT_D) are AC coupled. If they input an audio signal with a maximum amplitude of 2V RMS, this will result in a voltage of +/- 2.8Vpp on the Analog input pins. Specifically, the voltage will swing negative on the Analog input pins of the TPA3250. This seems to violate the absolute maximum specs noted above. Can you please explain if a bipolar input is tolerated on the TPA3250.

I would appreciate your help on this matter. Thank you and stay safe.

Regards,

Cedrick

over 3 years ago

0 Sam(MPAA) Zhang over 3 years ago

TI__Mastermind 19080 points

Hi Cedrick,

As you said, the analog input is AC coupled. On the device's side, the INPUT_x pins are biased to ~3.5V. So there will not be any negative swing range.

Thanks!

Regards,

Sam

0 Cedrick over 3 years ago in reply to Sam(MPAA) Zhang

TI__Expert 8270 points

Hello Sam,

Thank you for your support.

May I know if this is stated on the datasheet? I'm unable to find it and wonder if this is provided. Thanks.

Regards,

Cedrick

0 Sam(MPAA) Zhang over 3 years ago in reply to Cedrick

TI__Mastermind 19080 points

Hi Cedrick,

I didn't found it on datasheet either...

Well, it's a common design on the input stage of class-d amps with analog input. And typically it's biased at the middle of input range. As you are using AC coupling, the DC bias voltage on two sides of the coupling capacitor can be different, so no worry about this.

Thanks!

Regards,

Sam

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TPA3250: Analog input range