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TLV320AIC3101 Input protection

Lee Shaw
Prodigy 110 points
Other Parts Discussed in Thread: TLV320AIC3101

Hi All,

I'm using the CC85XX Dev Kit which uses the TLV320AIC3101 codec configured for stereo line inputs.

From the TLV320AIC3101 datasheet the absolute min/max analog input seems to be –0.3 to AVDD + 0.3. If the hardware I connect to the line-in of the codec has potential voltage levels up to say 10V, what would be considered a good way to protect the inputs of the codec from being overdriven or damaged?

One solution maybe that I can put some hardware together to monitor the signals for clipping and indicate this, so if zener or TVS diodes are considered OK I could live with that.

Does anyone have any thoughts on this please?

Thanks

  • 0
    TI__Mastermind 28585 points

    TV's or zener's would be a good choice.

  • 0 in reply to Converter Apps
    Prodigy 110 points

    Hi Converter Apps,

    Could you point me in the direction of any suitable products? Do TI have anything appropriate?

    I have just been looking at the ESD3V3S1B Infineon part, which seem to be particularly aimed for use in audio products. Their Vrwm of +/-3.3V seems appropriate, although the clamping voltage can be as high as 7V. I presume this may still cause damage to the codec. They are bidirectional parts too. I presume unidirectional parts are more applicable here.

    Thanks in advance for any pointers.

  • 0 in reply to Lee Shaw
    TI__Mastermind 28585 points

    Hi Lee,

    I don't have any direct experience using input diode clamps since I don't typically have to interface to the higher input voltages but a simple Google search for input protection diodes yields lots of hits. I know that TI makes ESD input protection devices but I don't think these are intended for this type of application since ESD is typically higher voltage and very low current. You could check with them on the Interface Forum.

    You definitely want to keep the voltages to the datasheet limits to insure that the inputs aren't damaged.

    If anyone else reading this has any experience with a specific part number, feel free to jump in with your advice.

  • 0 in reply to Converter Apps
    Prodigy 110 points

    Could it be as simple as connecting four 1n4148 signal diodes in series between say L1RP and L1RM of the codec, giving a forward conduction voltage of say 2.8V?

    Then with a second 'four diode chain' connected in the opposite direction, have protection of +/- 2.8V?

    Thanks in advance for any advice.

  • 0 in reply to Lee Shaw
    TI__Guru 62006 points

    I would use products that are specifically made for this purpose. I am not at liberty to suggest a specific part but if you search the web for "transient suppressor ESD diode" you'll find plenty of third party products that will solve your problems.

  • 0 in reply to Dominik Hartl11
    Prodigy 110 points

    Thanks for your response.

    My concern is that all parts I've seen have clamping voltages much higher than their breakdown voltage.

    I may be interpreting this incorrectly, but if I have a suppressor with a breakdown voltage of 3V3 the clamping voltage can be many volts higher = damaged codec.

    If I have a clamping voltage of 3V3, the breakdown voltage will be well within the range that the codec would normally operate within = chopped audio.