• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 33 subscribers
  • Views 465 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TCA9517 - Output source current

Kawai
Guru 19785 points
Other Parts Discussed in Thread: MSP430F5659, TCA9517

Hi Team,

Out customer will use TCA9517 with MSP430F5659 on the B side of the device. MSP430 VOL specification is in the following table.

Would  there be any source current from TCA9517 B side to MSP430 ?

I am asking this question because TCA9517 B side requires VOL < 0.4V for normal operation.
MSP430 would not be able to keep VOL < 0.4, unless its sink current is lower than 2mA.

Best Regards,
Takushi KAWAI

  • 0
    TI__Mastermind 30280 points

    Kawai-san,

    The MSP430 has to be able to drive the pull-up resistor low.

    If you know your VCC value, and you know from the MSP430 table above what current (Imax) you do not want to exceed, you can select a pull-up resistor such that VCC/R < Imax. This sets the limit on the strongest pull-up resistor you would want to use.

    Figures 3 and 4 on the MSP430F5659 datasheet (page 58) will give you an even better idea of the EXACT current where VOL=0.4V

    The amount of current that will be coming from the 0.5V offset voltage on the B side of the TCA9517 is negligible compared to the current through the pull-up resistor.

    Regards,

    Brian

  • 0 in reply to Brian Berner
    Guru 19785 points

    Hi Brian-san,

    Thank you for your quick reply.

    We will promote these devices together and ask them to use the pull-up resistor to meet 2mA of sink current with margin.

    Best Regards,
    Kawai