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ESDS311: ESD protection for microphone inputs on the TLV320AIC3106 codec

Dean Hofstetter
Expert 2565 points
Part Number: ESDS311
Other Parts Discussed in Thread: ESDS312, STRIKE

Tool/software:

I started a discussion over in the Audio forum about ESD protection on the mic inputs.  They suggested I try again over here.  Is there any ESD device I can put on the mic inputs to protect the 3106?  This part was recommended (www.ti.com/.../ESDS311), but the clamping voltage is too high.  In fact I can't find any ESD protection device that will help when the working voltage (3.3V) is very close to the absolute max voltage the IC can handle (3.9V).  Any recommendations?

Thanks, Dean

  • +1
    TI__Genius 14590 points

    Hi Dean,

    This is a common issue when trying to protect a low voltage interface when the downstream ICs have low IO voltage ratings as well. 

    It's important to note that clamping voltage is a transient spec while the abs max ratings in the audio codec are for DC conditions. There is typically some margin between the DC abs max failure voltage and transient failure voltage.

    One way to test the IC transient abs max voltage would be to use a transmission line pulse (TLP) generator to inject a pulse into the codec IC and measure the IV curve to see at what TLP current it would fail. This TLP current can be correlated with IEC 61000-4-2 ESD voltages. 

    If you only need to protect from lower kV ESD voltages, perhaps this diode could still protect the IC. Do you know what level of IEC ESD protection you're looking for? 

    Regards,

    Sebastian 

  • 0 in reply to Sebastian Muriel
    Expert 2565 points

    I don't know what IEC ESD protection level we require.  We get a few field failures a month that might be linked to an ESD strike on the mic inputs.  Currently going through a redesign and looking to improve that area.  Our current ESD device clamps anywhere between 10V and 15V depending on the Ipp current.  Your ESDS312 device clamps anywhere between 5V and 6.5V, which is a large improvement.  It still exceeds ABS max voltage, but as you say transient voltage is different than DC voltage.  I think we'll go with the ESDS312 device in the redesign and hope for an improvement with field failures.

    Thanks, Dean

  • 0 in reply to Dean Hofstetter
    TI__Genius 14590 points

    Hey Dean,

    I agree the ESDS312 is a large improvement in clamping performance and will better protect your circuitry. If you're changing the PCB layout, here are some helpful guidelines for improved ESD immunity in our ESD Protection Layout Guide.

    Regards,

    Sebastian