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TPS3808: dv/dt limits on MR pin

Danilo A.
Mastermind 28680 points
Part Number: TPS3808

Hi Team,

A customer has an inquiry regarding MR pin of TPS3808. Are there dv/dt limits on MR (i.e. can MR slowly transition from Vdd to GND and from GND to Vdd?)

Regards,

Danilo

  • 0
    TI__Mastermind 28680 points

    Hi Team,

    The customer also wants to confirm if the MR pin can go above VDD since most logic devices allow the input to go 1 diode above VDD if the current is limited to less than 10mA. Other logic devices do not have a clamp on their inputs (sometimes this is called an ESD diode). Does this device have that internal diode?

    Regards,

    Danilo

  • 0 in reply to Danilo A.
    TI__Genius 9375 points

    Hi Danilo,

    It is okay if MR slowly transitions. There is a voltage level low and voltage level high at 0.3 x VDD and 0.7 x VDD. These need to be crossed for the level low or high to be properly recognized, so in between this range if the ramp up or down is too slow, the output can be undefined. In regards to your second question, MR should be okay going at least 1 diode above VDD as you mentioned. We still need to remain under VMR max. The device has internal ESD protection diodes.

    Thanks,
    Abhinav.

  • 0 in reply to Abhinav.Sharma
    TI__Mastermind 28680 points

    Hi Abhinav,

    Thank you for your response. I would like to clarify if according to Section 7.1 Absolute Maximum Ratings, the VMR max is 7V. If the VDD is 3.3V, can TPS3808 withstand the 7V input at MR pin? The voltage across the ESD diode will be 7V - 3.3V = 3.7V. 

    Regards,

    Danilo

  • 0 in reply to Danilo A.
    TI__Mastermind 28680 points

    Hi Abhinav,

    We received some follow up inquiry from the customer.

    1. Is the ESD diode rated for the standard 10mA of current flow?

    2. For slow transitions, is there no damage for slow crossing and if the crossing is faster than the RESET delay, will the RESET delay hold the output in the asserted state once the output goes low?

    Regards,

    Danilo

  • 0 in reply to Danilo A.
    TI__Genius 9375 points

    Danilo,

    Sorry for the delay. For your inquiry:

    I have reached out to design regarding the specific details for the device. Since some of this could be sensitive information, I will reply to your email to discuss the details.

    Thanks,
    Abhinav.