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TCAN2845-Q1: If I unuesd VEXCC, I only use VCC1, how should the VEXCC pin be handled

zhang hongxin
Prodigy 10 points
Part Number: TCAN2845-Q1

Hi team:

     If my design does not require the use of VEXCC and only needs VCC1 and VCC2, how should the VEXMON, VEXCTRL, and VEXCC pins be handled? In the schematic design, can they be left floating? If left floating, what issues might arise?

  • 0
    TI__Mastermind 24415 points

    已经收到了您的案例，调查需要些时间，感谢您的耐心等待。

  • +1 回复 Eirwen
    TI__Mastermind 24415 points

    If VEXCC is unused VEXMON must be shorted directly to VSUP

    If VEXCC is unused VEXCTRL can be left floating

    If VEXCC is unused VEXCC can be left floating

  • +1 回复 Eirwen
    Prodigy 10 points

       Can you help me check the design? I will not use VEXMON VEXCTRL VEXCC. I have uesd 1R connect VEXMON and VSUP, the design is correct?

  • +1 回复 zhang hongxin
    TI__Mastermind 24415 points

    If VEXCC is not going to be used in application then you need to do the following:

    1. Short VSUP to VEXMON - don't add a 1ohm resistor - it should be shorted.

    2. You can leave VEXCTRL floating

    3. You can leave VEXCC floating

    The rest of the schematic - from what is shown - looks okay. Please remember to put 100nF decoupling caps as close to the power input pins as possible. They also aren't showing the reverse polarity blocking diode and I'd suggest they add that - if they haven't already (it might just not be shown in schematic). You may also want to add a little more capacitance on the VSUP pin for EMI reasons. 

    Please let me know if you have any questions!

  • +1 回复 Eirwen
    Prodigy 10 points

    Thanks for your reply. But in my first use, if I use VEXMON VEXCC for functional debugging, a sampling resistor connect  VEXMOC and VSUP.However, during mass production of the final solution, I may not use VEXCC. Therefore, VEXMON and VSHUP cannot be shorted directly. I can only replace the sampling resistor with a 0R component and leave other pins floating. Would this approach be feasible?

  • +1 回复 zhang hongxin
    TI__Mastermind 24415 points

    That should be okay - if you may use it during test/debug using a 1 ohm resistor is fine - just be sure to keep VEXCC disabled during production builds.