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ESD204: Utilization on I/O Detection Circuit as Well as I2C

Mike Mrazik
Prodigy 20 points
Part Number: ESD204
Other Parts Discussed in Thread: TPD4E02B04

Tool/software:

Hello,

I currently use an OnSemi ESD8004 which appears similar to the ESD204DQAR.  The OnSemi part is not only obsolete, but I've also had issues with it getting damaged somehow in the below circuit.

The circuit detects when a certain battery type is plugged in, there is a pull down resistor in the battery and then the pull up on this circuit, therefore creating a divider that triggers a comparator based on the measured voltage.  I've had this ESD8004 device get damaged, with either a short to ground or some current draw to ground which causes a "detection" on my circuit when nothing is attached.  I am unsure how this is occurring, but I'd like to change to the ESD204DQAR from TI, do you see any issues with this circuit using the ESD204?  The expectation is that no current should conduct through the ESD device when there is no ESD event, or if there is a current its miniscule and wouldn't be enough to create a sizeable voltage drop across the 10k pull up resistor.

Only 1 channel is shown in that 4 channel part, the other 3 have SDA/SCL on 2 of the lines, and another identical circuit for a different type of battery on the 3rd channel.

Thanks,
Mike

  • 0
    TI__Expert 4910 points

    Hi Mike,

    What voltage is being run? And are the ESD diodes being used to protect the microcontroller, if so, what is the part number? 

    Best,

    McKenzie

  • 0 in reply to McKenzie Eaker
    Prodigy 20 points

    Hi McKenzie

    3.3V system, the SDA/SCL lines are pulled up to 3.3V.  The ID lines (that I've had issues with) are pulled up to 3.3V.  

    ID lines connect to a comparator as shown in the image, then the output of the comparator give a 3.3V or 0V signal to the processor.  SDA/SCL directly connect to the processor, which is a Renesas S5D9 series on this application but also use same part on SDA/SCL lines on a S3A1 series.

    When a battery is attached, the ID lines will drop due to a roughly 10k pulldown resistor in the battery.

    Thanks

    Mike

  • 0 in reply to Mike Mrazik
    TI__Expert 4910 points

    Hi Mike, 

    Thanks for letting me know! I am not sure why the ESD8004 is causing issues, but it might be the snapback that occurs. 

    I think ESD204 will be a good option, but I am worried about the clamping voltage. It might be too high to protect the microcontroller. Next option would be TPD4E02B04, it has a lower clamping voltage, but it has less than ESD protection (12kV). 

    Best,

    McKenzie

  • 0 in reply to McKenzie Eaker
    Prodigy 20 points

    Hi McKenzie

    Can you clarify what is meant by snapback?

    Regarding TPD4E02B04, if that has a lower clamping voltage would that be conducting during normal operation? 

    Thanks

    Mike

  • 0 in reply to Mike Mrazik
    TI__Expert 4910 points

    Hi Mike, 

    Snapback refers to a feature of some diodes. The IV curve below from ESD8004 gives a visual. Some diodes will have a shallow snapback and others will have a deep snapback. Snapback means the diode will reach its breakdown voltage (also known as trigger voltage) then will "snapback" to a voltage lower than the working voltage (known as holding voltage). Deep snapback devices can allow for a clamping voltage similar to the working voltage of the diode. 

    There should be no issues with TPD4E02B04 turning on during normal operation. It has a working voltage of 3.6V with a breakdown of 6.4V.

    Best,

    McKenzie