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Output protection for DAC7563

Oscar Gomez Fuente
Expert 2066 points
Other Parts Discussed in Thread: DAC7563, DAC8760, OPA2140

Hi,

I would like to protect the output of the DAC7563, the output is going to have a range of -5V to 5V and I was thinking to use a bidirectional TVS simliar to this part number from littlefuse SMAJ5.0CA with VR = 5V: http://www.digikey.es/product-detail/en/SMAJ5.0CA/SMAJ5.0CALFCT-ND/762463

Could it be a good solution?

Thank you so much. Best Reagrds.

  • 0
    TI__Genius 10615 points
    Hi Oscar,

    The TVS diode at ±5 V it will only be conducting ±800 μA, which for most buffers would not affect the performance. However in order to give you a more confident answer, it would be necessary to take a look at the schematic of your bipolar output implementation.

    What are the expected transients on the output that you are trying to protect against?
  • 0 in reply to Eugenio Mejia
    Expert 2066 points

    Hi Eugenio,

    This is my design:

    I would like to protect as far as possible the outputs SP_TH1 and SP_TH2 against ESD and I have to meet EMC.

    Best regards.

    protect as far as possible the

  • 0 in reply to Oscar Gomez Fuente
    TI__Genius 10615 points

    Oscar,

    I can't accurately speak for a MAX device so I would suggest checking with their support team but from page 9 of the MAX44267 datasheet, I don't foresee the 800 μA load affecting your circuit.

    In addition, we have a EMC/EMI Protection DAC TI Design that uses an output protection circuit that might be useful for you. The document certifies another of our DACs, DAC8760, passing the IEC61000-4 suite of tests. It explains the different layers of protection as well as the specific tests performed. The design process is not associated with any particular output stage. Maybe you can leverage some of the information contained in that document to design an output protection that suits your needs.

  • 0 in reply to Eugenio Mejia
    Expert 2066 points

    Hi Eugenio,

    Finally, I decided to use an opa2140 with +12V and -12V power supply. My output it's going to be in a range of +5V to -5V, but the op-amp is going to be feed with +/-12V, then the ESD protection is going to be fixed to 12 Volts.

    I'm going to use the following configuration according to the EMC/EMI Protection DAC TI Design:

    1º- One SMBJ12CA TVS to protect against ESD.

    2º. One WE inductor with 600Ohm@100Mhz Ir= 1000mA to avoid EMI issues.

    3º.- One SCR diode  SBR0220T5-7 to protect against high-level positive input voltage.

    What do you think about my design?

    My main aim it's to meet with EMC.

    Beat regards.

     EMC/EMI Protection DAC TI Design