TLV320AIC20K: Microphone and Earphone Connection

Hi, Ganesh,

Our audio converters don't require additional op-amp to connect microphone or earphones. The additional amplifier is only suggested if your application requires more output power.

Best regards,
Luis Fernando Rodríguez S.

Hi, Luis,

Thanks for the reply.

pl go through the following points

1. The method of connection between microphone (single ended) and TI part TLV320AIC20K is suggested in the datasheet, but the same for Earphone is not mentioned.

2. I need to connect any one pair (HNSO+/- or HDSO+/- or SPKO+/-) - 150 OHM to the single ended Earphone (with specs already mentioned in the thread).

Existing Solution:

I have used LM8272 to combine +/- signals to give single ended output for my Earphone

Concern:

How to cater the possible Impedance Mismatch due to use of LM8272 in line?

(The assumed, matched impedance -150 OHM is disturbed due to insertion of LM8272)

Suggestion is required on the same

Reg,
Ganesh

Hi, Ganesh,

In order to connect a 150ohm single ended earphone, you would need to use the HDSO outputs, which are designed for 150ohm loads. You would need to connect an AC-coupling capacitor (around 0.1uF) between the HDSO+ output and the earphone load. There's no need to add an external op amp since these outputs are designed for this kind of loads. However, you may add this op amp at the outputs directly. You only need to connect the AC-coupling capacitor as I mentioned.

Best regards,
Luis Fernando Rodríguez S.

Hi, Luis,

Thanks for the reply.

I have kept option for both pairs (HNSO+/- and HDSO+/-) - 150 OHM to the single ended Earphone and I have used LM8272 to combine +/- signals to give single ended output for Earphone.

I didn't understand following line in your previous reply

"However, you may add this op amp at the outputs directly."

Concern:

How HDS0+ or HNSO+ alone can cater Single Ended Load as it is not mentioned in the datasheet?

What should be the status of HDS0- or HNSO- pins when HDS0+ or HNSO+ is connected to Single Ended Load?


If LM8272 has to be used,

the probable impedance mismatch (due to insertion of LM8272) is not addressed in reply.

Suggestion is required on the same

Reg,
Ganesh

Hi, Luis,

Thanks for the reply.

Please find the attached ".jpeg" file which has detailed connection

between Earphone(single ended) with TI part TLV320AIC20K which is done in

our present design.

As you can see in the attached image,

I have kept option for both pairs (HNSO+/- and HDSO+/-) - 150 OHM to the

single ended Earphone and I have used LM8272 to combine +/- signals to

give single ended output for Earphone

I didn't understand following line in your previous reply

"However, you may add this op amp at the outputs directly."

Concern:

How HDS0+ or HNSO+ alone can cater Single Ended Load as it is not

mentioned in the datasheet?

What should be the status of HDS0- or HNSO- pins when HDS0+ or HNSO+ is

connected to Single Ended Load?

If LM8272 has to be used,

the probable impedance mismatch (due to insertion of LM8272) is not

addressed in reply.

Suggestion is required on the same

Reg,

Ganesh

> A Message from the TI E2E™ Community

>

> Luis Fernando Rodríguez S. [http://e2e.ti.com/members/4296757] replied

> to TLV320AIC20K: Microphone and Earphone Connection

> [http://e2e.ti.com/support/data_converters/audio_converters/f/64/p/580457/2142024#2142024].

>

> Hi, Ganesh,

>

> In order to connect a 150ohm single ended earphone, you would need to use

> the HDSO outputs, which are designed for 150ohm loads. You would need to

> connect an AC-coupling capacitor (around 0.1uF) between the HDSO+ output

> and the earphone load. There's no need to add an external op amp since

> these outputs are designed for this kind of loads. However, you may add

> this op amp at the outputs directly. You only need to connect the

> AC-coupling capacitor as I mentioned.

>

> Best regards,

>

> Luis Fernando Rodríguez S.

>

> You received this notification because you subscribed to the forum.  To

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Hi, Ganesh,

The differential outputs in our audio converters can be used as single-ended as well. You would need to connect the positive output and the negative outputs can be left floated.

Regarding the LM8272 insertion, I didn't find anything to modify. There shouldn't be any impedance mismatch problem with this connection.

Best regards,
Luis Fernando Rodríguez S.