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DAC43608: Question about negative digital input voltage of absolute maximum ratings.

Kazuya Nakai59
Guru 20620 points
Part Number: DAC43608
Other Parts Discussed in Thread: SN74AHC595

Tool/software:

Hello guys,

One of my customer is considering using DAC43608 for their next products.

At this moment, they have the following question.
Could you please give me your reply?

Q.
I think DAC43608 datasheet says that the Input voltage(Vi) more less -0.3V (For example -0.5V) is allowed as long as Input clamp current is limited within +10mA~-10mA.
Is my thought correct?

Your reply would be much appreciated.

Best regards,
Kazuya.  

  • 0
    Guru 20620 points

    Hello guys,

    The customer needs your reply as soon as possible.

    Could you please give me your reply?

    Thank you and best regards,
    Kazuya.

  • 0 in reply to Kazuya Nakai59
    TI__Guru 53263 points

    Hi Kazuya-san,

    That is not exactly the correct way to interpret the specification.  Generally, the voltage limits are there to illustrate that the ESD cells will start conducting significant current if the input is reversed biased beyond that limit.  If you limit your current, to below the value that the diode would normally conduct, you would not measure a voltage drop across the diode.  

    In this case, I cannot provide an exact number for the current limit to prevent the pin from going <-0.3V, but I would suspect it would be 1-2mA.

    Thanks,

    Paul

  • 0 in reply to Paul_Frost
    Guru 20620 points

    Hi Paul,

    Thank you very much for your reply.

    Could I ask you the following questions as additional?

    Q1.
    For example, SN74AHC595 datasheet says that the Input voltage(Vi) below -0.5V (For example -0.6V) is allowed as long as Input clamp current(Iik) is limited within -20mA.
    Is DAC43608 input current meaning different from this SN74AHC595 input clamp current(Iik) meaning ?

    Q2.
    Can DAC43608 digital input voltage of absolute maximum rating not be allowed to violate even if the input current is less than 10mA? 

    Thank you again and best regards,
    Kazuya. 

  • 0 in reply to Kazuya Nakai59
    TI__Guru 53263 points

    Hi Kazuya-san,

    We nevery recommend that the absolute maximum limits be violated.  From practical experience, we have seen that damage is unlikely when the current is limited to small amount, <2mA.  It is hard to guarantee the behavior as duration and factors could effect the ESD cell.

    The current limit in the datasheet is a general absolute maximum applied to all pins, added to clarify that this is a low power device and not designed to handle >10mA on any pin.

  • 0 in reply to Paul_Frost
    Guru 20620 points

    Hi Paul,

    Thank you very much for your supports.

    Can the digital input voltage not allowed to violate the absolute maximum rating even if the undershoot is very short?
    Their undershoot peak voltage is -1V and the undershoot width is about 2ns.

    Thank you again and best regards,
    Kazuya.

  • 0 in reply to Kazuya Nakai59
    TI__Mastermind 30168 points

    Hi Kazuya-san,

    The answer here would be the same as Paul's from yesterday.

    Damage is unlikely if the current is limited and for a short time, but we still would not recommend violating the absolute maximum voltage ratings or current ratings. We wouldn't be able to guarantee behavior for this use case because we don't characterize the device under these conditions. 

    Best,

    Katlynne Jones