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DS90LV049: variation range of internal resistor value for failsafe biasing

Go
Genius 4155 points
Part Number: DS90LV049

Hi,

Does someone have a data for the variation range of internal resistor value for failsafe biasing?

Thanks

Go

  • 0
    TI__Mastermind 43795 points

    Go,

    I do not have access to the design documentation at this time (so I could give you a range).  Based on the typical input current data, I would say that a typical value is ~ 200K Ohms.  The failsafe prevention is largely due to an input threshold voltage offset (typically 15mV). 

    Regards,

    Lee

  • 0 in reply to Lee Sledjeski
    Genius 4155 points
    Hi, Lee-san

    Thank you for your comment.

    How do you estimate the resistor typ value (～200kΩ ) from the typical input current data(+/- 4uA)？

    Regards,

    Go
  • 0 in reply to Go
    TI__Mastermind 29635 points
    Hi Go,

    This can be estimated by determining the amount of input current that is present when VIN is high. If there were no fail-safe bias network, then this would virtually eliminate current flow from VDD to the LVDS input when the input goes high.

    When VIN = 2.8 V, according to the datasheet, the voltage drop from VDD to VIN = 0.8 V. The input current in this scenario if 4 uA. To determine the value of the fail-safe pullup resistor, 0.8 V/ 4 uA = 200 kOhms, typical.

    Regards,

    Michael