BUF634A: Headphone Amplifier

Sadanori Kato

Part Number: BUF634A
Other Parts Discussed in Thread: TPA6120A2, TPA6120A2EVM

Hi,

For the headphone amplifier, could you please let me know if there are TI solution which meets the following requirements?
I am considering suggesting to use BUF634A with BTL to our customer.

<Requirements>
- Single power supply voltage : 12V ~ 18V
- Load impedance : 8ohm
- Output power : > 500mW

Best regards,
Kato

over 5 years ago

0 kai klaas69 over 5 years ago

Guru 140200 points

Hi Kato,

TI offers special headphone amplifiers:

Kai

0 Sadanori Kato over 5 years ago in reply to kai klaas69

Guru 36540 points

Hi Kai-san,

Thank you for the informatio.

Does TPA6120A2 meet our requirements?

Best regards,
Kato

0 Ivan Salazar over 5 years ago in reply to Sadanori Kato

TI__Guru** 114155 points

Hi Kato-san,

TPA6120A2 is good for your requirements.

Headphone speaker loads are usually 16 or 23 ohms, so the device is not rated for 8 ohms. However it can still drive this load. If you need some tests with 8 ohm load to confirm its support I can do that early next week.

Best regards,
-Ivan Salazar
Applications Engineer - Low Power Audio & Actuators

0 Sadanori Kato over 5 years ago in reply to Ivan Salazar

Guru 36540 points

Hi Ivan-san,

Thank you for your response.

Could you please confirm whether TPA6120A2 can work with 8ohm normally?
I am concerned about the thermal capacity when TPA6120A2 is used at 500mW output.

Best regards,
Kato

0 Ivan Salazar over 5 years ago in reply to Sadanori Kato

TI__Guru** 114155 points

Hi Kato-san,

From section 7.1 of the data sheet, we can say 8ohm is supported as this is the minimum impedance load.

Regarding 500mW, I could verify in the lab over the next week.

Best regards,
-Ivan Salazar
Applications Engineer - Low Power Audio & Actuators

0 Sadanori Kato over 5 years ago in reply to Ivan Salazar

Guru 36540 points

Hi Ivan-san,

Thank you for your reply.

I am looking forward to getting the detailed information from you.

Best regards,
Kato

0 Ivan Salazar over 5 years ago in reply to Sadanori Kato

TI__Guru** 114155 points

Kato-san,

Current demand from the device for 8 ohm load is too high related to 16 or 32 ohm loads.
The device is most likely heating up to protecting itself if try to reach 0.5W. Based on plots on page 7 of data sheet, the dissipated power would rise dramatically if considering 8 ohm load.

As you can see from figure 6 on the data sheet, the device can reach 0.5W with 32 ohm load only when using highest supply voltage (differential 30V).

Higher efficiency would be best for low impedance values, does Class-D can be an option for this application?

Best regards,
-Ivan Salazar
Applications Engineer - Low Power Audio & Actuators

0 Sadanori Kato over 5 years ago in reply to Ivan Salazar

Guru 36540 points

Hi Ivan-san,

Thank you for the information.

Unfortunately, the target is high-performance audio application. So, the Class-D amplifier cannot be chosen.
Is it difficult to reach the 0.5W output even if using TPA6120A2 with BTL mode?
Additionally, please let me know if you have more reasonable solution.

Best regards,
Kato

0 Ivan Salazar over 5 years ago in reply to Sadanori Kato

TI__Guru** 114155 points

Kato-san,

I didn't know BTL could be an option. Will let you know on that test by this Friday.

Best regards,
-Ivan Salazar
Applications Engineer - Low Power Audio & Actuators

0 Sadanori Kato over 5 years ago in reply to Ivan Salazar

Guru 36540 points

Hi Ivan-san,

Thank you for your continuous support.

I am looking forward to hearing the good information from you.

Best regards,
Kato

0 Ivan Salazar over 5 years ago in reply to Sadanori Kato

TI__Guru** 114155 points

Hi Kato-san,

You would need at least ~14V or higher supply voltage in order to reach 0.5W at 8-ohm load in BTL connection.
The device will still heat up considerably so you should consider this when designing the layout and selecting package; DWP has best thermal performance compared to RGY.

Best regards,
-Ivan Salazar
Applications Engineer - Low Power Audio & Actuators

0 Sadanori Kato over 5 years ago in reply to Ivan Salazar

Guru 36540 points

Hi Ivan-san,

Thank you for the information.

Has TPA6120A2 been tested with the default output series resistors on TPA6120A2EVM?

Best regards,
Kato

0 Ivan Salazar over 5 years ago in reply to Sadanori Kato

TI__Guru** 114155 points

Hi Kato-san,

Yes, I tested the EVM as is.

Best regards,
-Ivan Salazar
Applications Engineer - Low Power Audio & Actuators

0 Sadanori Kato over 5 years ago in reply to Ivan Salazar

Guru 36540 points

Hi Ivan-san,

Thank you for your response.

I understand.

Best regards,
Kato

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BUF634A: Headphone Amplifier