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ESDS304: 3.3V SPI Transient Protection Using TVS Diodes

Al
Prodigy 40 points
Part Number: ESDS304
Other Parts Discussed in Thread: ADS8681

Hi there. 


I'm using 3.3V 10MHz SPI signals in a design and need to protect them from transients.


I found the ESDS304DBVR and was wondering if it's suitable for my application.


The part (ADS8681) with the lowest tolerance along the path in this design has a maximum input voltage rating of 3.6V.


The ESDS304DBVR is rated @ Vrwm = 3.6V, Vbrf = 4.5-7.5V and Cline = 2.8pF max, though I'm not sure about Vclamp though. Is it suitable among the stated Ipp variations?


If not is there another suitable device that you can recommend or perhaps another technology?

Thanks,

Al.

  • 0
    TI__Expert 8471 points

    Hi Al,

    I think this device would suit your application very well. While the clamping voltage of this device does exceed the abs max of the digital I/Os in the ADC, this does not mean it will fail to protect your system from transients. In most IC datasheets, the abs max table refers to constant DC voltages (ie. voltages that last longer than 20 us). ESD and surge transients last only a few nanoseconds and microseconds, respectively. This means that the digital I/O pins on the ADC should be able to handle transient voltages higher than 3.6 V. The only way to determine the max transient voltage a device can withstand is to run a TLP curve on each pin and see what voltage the device fails at. Unfortunately, most devices in the industry do not come with that data available. 

    Regards,

    Matt Smith 

  • +1 in reply to Matt Smith3
    Prodigy 40 points

    Understood.

    Thanks for the quick reply Matt.

    Al