SGTL_5000 Input Mic

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SGTL_5000 Input Mic

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GSXR100038
Contributor II

Hello,

I would like to have some advice, I use the CODEC SGTL 5000 with a microphone input. Should I enter a signal with an offset (+1.5V and -1.5V) or without an offset (+3V)?GSXR100038_0-1665729447715.png

GSXR100038_1-1665729545553.png

GSXR100038_2-1665729653014.png

Thank you in advance for your helps.

Regards

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JozefKozon
NXP TechSupport
NXP TechSupport

Dear Yann,

please see below an answer from an application engineer I have contacted. Please make sure you do not exceed the maximum ratings stated in the SGTL5000 datasheet. Otherwise the component will be damaged.

JozefKozon_2-1666163140088.png

DESCRIPTION

The Mic input pin should not have minus voltage, otherwise it may damage. So customer could input voltage above 0V on Mic input pin.

With Best Regards,

Jozef

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GSXR100038
Contributor II

Hello Jozef,
Thank you for your answer but I think your answer is probably wrong.  

'So customer could input voltage above 0V on Mic input pin

After the capacitor C7 you no longer have an offset.  

GSXR100038_0-1666165509781.png

Thus you'll have this configuration at the input of MIC (pin 10). Yes you're right about the maxi value which should not exceed 2.83 pp V.  

GSXR100038_1-1666165781600.png

 

 

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JozefKozon
NXP TechSupport
NXP TechSupport

Hello Yann, 

yes, you are right, the bias voltage should move the signal to the positive voltage. Alternatively you can add there a diode to create a clamper circuit, to make sure, that the voltage will not drop below 0V. But I am not sure how it will influence the signal. 

Still please test first to apply positive signal on the MIC pin and you can then step be step move the signal below 0V. 

JozefKozon_0-1666171082102.png

With Best Regards,

Jozef

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GSXR100038
Contributor II

Hi JozefKozon,

Thank you for your recommendations. Now I think how it's work with the MIC input and the maximum values.

Regards.