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TCAN1043-Q1: What is the state when INH=Low?

Kazuya Nakai59
Guru 21595 points
Part Number: TCAN1043-Q1
Other Parts Discussed in Thread: TCAN1043, TCAN1042-Q1

 Hello guys.

 One of my customers is trying to evaluate TCAN1043-Q1 for their next products.

 They have a few questions as the follows. Could you please give me your reply?

Q1. On page 33 of TCAN1043 datasheet (SLLSEV0D),

 we can see that "The INH pin is high for normal, silent, Go-to-Sleep, and standby modes. It is low when in sleep mode."

 Does "It is low" in this sentence mean high-z state or real low level? Because we can't see any MOSFET to pull INH low in 10.2 Function Block Diagram on page 19. 

 Q2. How to treat INH pin when INH pin not used? Is it OK to leave INH open? Or is it better to tie to VSUP?

 Your reply would be much appreciated.

 Best regards,

 Kazuya.

  • 0
    TI__Guru 62920 points

    Hello Kazuya-san,

    The INH output is never driven low by the device.  It is either pulled to VSUP via a pull-up FET (i.e., in standby, silent, normal, or go-to-sleep modes) or made high-Z (in sleep mode).  It is common to place a weak pull-down resistance externally on this net to ensure the voltage decays to 0 V when INH is high-Z; a common value is 100 kOhm.  (If INH connects to the enable control of a power regulator, often some pull-down resistance or current source is included internally to the regulator.)

    If INH is unused it is best to keep it disconnected.  There wouldn't typically be an issue connecting it to VSUP, either, but that is not required and may end up subjecting it to transient overvoltages that could occur on the battery line in a real system.

    If INH is not needed in an application, it may be worth considering a simpler 8-pin transceiver like TCAN1042-Q1 instead.

    Regards,
    Max

  • 0 in reply to Miguel Robertson
    Guru 21595 points

     Hello Max,

     Thank you very much for your prompt reply.

     It is very helpful for the customer and me.

     Thank you again and best regards,

     Kazuya.