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DS26C32AT: Vcc Transient Above 7V

Mike Yu
Prodigy 10 points
Part Number: DS26C32AT


Question on component's ability to handle a transient on the Vcc line during power on lasting 1-2 ms.  With one of our power supplies, during power on, seeing a transient on the power line that would reach 12V-22V which lasted 1-2 ms.  Is there any protection on the Vcc line internal to the component that might allow it to handle this transient.

  • 0
    TI__Guru 50688 points

    Mike,

    Seeing that the device is being operated outside absolute maximum conditions, I cannot guarantee that the device will not be damaged by being powered on. 

    Looking at a previous thread, there are internal clamping diodes on the I/Os to provide overvoltage protection. 

    https://e2e.ti.com/support/interface-group/interface/f/interface-forum/730692/ds26c32at-internal-clamp-diodes

    I am not exactly sure about the clamping on the VCC pin. I am confirming this right now with another engineer. I'll reply again with updated information on this pin. However, I suggest that you develop a way to slowly ramp up the power supply voltage so you do not see those voltage spikes, or add some external clamping circuitry to counter this problem. Looking at the datasheet, I see that there is some ESD protection. ESD strikes, although tested in kV range, only last for ns at a time. Since you are seeing transients on the scale of ms, I would be careful with continuous power up/ power down with this device. 

    Regards,

    -Tyler

    After further review on the VCC pin, I would expect that repeated 12V-22V 1ms transients would eventually damage the device. Please try to operate the device within the recommended operating conditions listed in the datasheet.

  • 0 in reply to Tyler Townsend
    Prodigy 10 points

    Hi Tyler,

    Thank you for the reply. If we are expecting on a handful (5-10) of turn ons/offs, based on the circuitry of the part, would there be an expectation of damage to the device still? 

  • 0 in reply to Mike Yu
    TI__Guru 50688 points

    Mike,

    Since the device is operating outside absolute max conditions listed for the VCC pin, I cannot guaranteed that it will / will not damage the device. I would lean more towards that the device will most likely fail, since 1ms is quite a long time for a 22V voltage spike on VCC.

    Regards,

    -Tyler