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TPS3897: min & max value for hysteresis

Joey Christ
Intellectual 2350 points
Part Number: TPS3897


In the datasheet (April 2015), section 7.5 Electrical Characteristics, it provides a Typical Hysteresis Voltage of 5 mV but no min or max value. 

  • At a minimum, I need to know the Maximum Hysteresis Voltage (over operating temperature range)?
  • It would also be helpful to know the Minimum Hysteresis Voltage (over operating temperature range)?
  • +1
    TI__Mastermind 20750 points

    Hi Joey,

    The hysteresis for this device is internally regulated and any deviation is accounted for in the device overall accuracy.

    Jesse 

  • +1 in reply to Jesse Villanueva
    Prodigy 90 points

    Thanks Jesse, we are looking to see if TI can provide the min max Vhys values.

    The datasheet provides an overall accuracy for the Positive Going Threshold (VIT+) bus does not provide an overall accuracy for the Negative Going Threshold.

    Instead, it provides a typical Hysteresis voltage for the falling edge of Vhys=5mV typ. The falling edge voltage can be calculated as VIT- = VIT+ - Vhys

    Since only a typical Vhys value is provided, we are unable to bound the falling edge threshold voltage (VIT-).

    Please provide a min and max value for Vhys over device operating range or alternately provide a VIT- range (min and max) over device operating range?

  • 0 in reply to Paul Kmita
    TI__Mastermind 20750 points

    Hi Paul, 

    For our under voltage detection devices, hysteresis does not play into Vit- only in the Vit+.

    For reference, Vit-(max) = Vit * ( 1 - (device accuracy%)/100) while Vit+(max) = Vit * ( 1 + (device accuracy%)/100) + Hysteresis. 

    Jesse 

  • 0 in reply to Jesse Villanueva
    Prodigy 90 points

    Thanks Jesse, 

    For us to use the equasion we need to know t

    From the HW team

    There are other TI devices that work the way that you describe where a tolerance is provided for VIT- and a HYS value is used to calculate VIT+.

    However, per the TPS389 datasheet, the TPS389 provides a tolerance for the VIT+ and HYS value to calculate VIT-.

    VIT+ is defined by the tolerance (0.495 V to 0.505 V) and the Vhys (5 mV typ.) is then used to determine the VIT-.

     

    The datasheet only provides a typical value for Vhys. What we need to know is the range of Vhys (e.g. min and max).

  • 0
    Prodigy 90 points

    Hello Jesse,

    Did you get a chance to review the latest question?

     

    We need to know the worst case Vmin, which can only be determined by knowing the maximum hysteresis. Can TI provide the worst-case V(sense) falling or the worst-case hysteresis (max hysteresis)?

    Thanks

    Paul

  • 0 in reply to Paul Kmita
    TI__Mastermind 20750 points

    Hi Paul,

    Since the TPS3897 DS has provided the Vit+ for an under voltage detection device.

    The highlighted values are the min, typ, and max for the Vit+, to de-assert RESET.

    For the Vit-, Vsense to assert RESET, Vit- = Vit+ - Vhyst.

    Vit-(min) = .49V Vit-(typ) = .495 and Vit-(max) = .5V

    These values are tested across temperature.

    Jesse