TPA3221: Input Grounding

Kazuki Itoh

Part Number: TPA3221
Other Parts Discussed in Thread: TPA3255

Hi team,

I have a question about TPA3255.

When MODE pins are set to M1=0, M2=1 for PBTL mode, I need to ground audio inputs INPUT C and D (pins 16, 17).

Should the grounding be done mechanically using jumper pins like on the evaluation board, or can it be done electrically using FETs or transistors?

Also, the datasheet states that PBTL output becomes mono BTL when INPUT C (pin 16) is at HIGH level with DVDD voltage. What is the voltage threshold for this? Is it the same as VoH and VoL specified in section 7.5 STATIC DIGITAL SPECIFICATIONS?

Best regards,
Kazuki Itoh

1 month ago

0 Sydney Northcutt 1 month ago

TI__Mastermind 23150 points

Hello,

Thank you for reaching out. Please expect a response by tomorrow end of day.

Regards,
Sydney

0 Kazuki Itoh 1 month ago in reply to Sydney Northcutt

TI__Genius 11320 points

Hi Sydney,

Thank you. I'm looking forward to your response.

Best regards,
Kazuki Itoh

0 Sydney Northcutt 1 month ago in reply to Kazuki Itoh

TI__Mastermind 23150 points

Hello,

No jumpers, fets, or transistors are needed. These can be direct shorts to ground.

For the second portion of your question, what section of the datasheet are you referring to?

Regards,
Sydney Northcutt

0 Kazuki Itoh 1 month ago in reply to Sydney Northcutt

TI__Genius 11320 points

Hi Sydney,

Thank you.

Regarding second question, I think my customer is reffering to Table 1 of TPA3255 datasheet.

https://www.ti.com/lit/ds/symlink/tpa3255.pdf#page=1

Best regards,
Kazuki Itoh

0 Sydney Northcutt 1 month ago in reply to Kazuki Itoh

TI__Mastermind 23150 points

Hello,

I see. Since a high value is referenced to DVDD, you can refer to the digital thresholds in the datasheet on page at the top of page 8.

Regards,
Sydney Northcutt

0 Kazuki Itoh 1 month ago in reply to Sydney Northcutt

TI__Genius 11320 points

Hi Sydney,

This question concerns the method of switching the audio input grounding when the IC is designed to allow switching between BTL and PBTL modes on the board, rather than having a fixed PBTL output mode.

We are assuming that the output mode can be switched between BTL2 and PBTL on the board during use. In BTL2 mode, audio inputs C and D (pins 16, 17) are active, but in PBTL mode, these inputs need to be grounded.

Question: Can the grounding of these audio inputs be switched electrically using FETs or transistors, rather than mechanically using jumpers as shown in the evaluation board?

Best regards,
Kazuki Itoh

+1 Sydney Northcutt 1 month ago in reply to Kazuki Itoh

TI__Mastermind 23150 points

Hello,

The answer is yes, but the amplifier must be powered down. This can not be changed on the fly.

Regards,
Sydney Northcutt

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TPA3221: Input Grounding