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SN65HVD72: Hot plugging with connector without first-make power contacts

Stefan Olejniczak57
Prodigy 140 points
Part Number: SN65HVD72
Other Parts Discussed in Thread: SN65HVD75, SN65HVD78

Hello,

i plan to use the device in a point to point (i.e. no bus) configuration with two SN65HVD72 (one on each side). The slave device (without own power supply) is hot plugged to the master device, which besides data A and B also provides the power of +3.6V (max.) and GND to the slave. So i have a 4 pin connector (2 x data, 2 x power).

The question is now if there may exist a case of possible damage to the slave device, if any make-first-combination of the 4 contacts occurs during hot-plugging?

Example (for illustration):

Make + 3.6V first, then make signal A, then make GND, then make signal B.

Note that due to missing first-make power contacts any sequence of make-combination could be possible.

Thanks and best regards.

  • 0
    TI__Guru 53575 points

    Hi Stefan,

    Thank you for your detailed explanation. SN65HVD72 does support hot plugging. When the device is unpowered, the A and B lines will be high impedance and only allow a small leakage current to GND or Vcc. The device is also designed for glitch-free power-up so the bus can remain stable during plugging. SN65HVD75 and SN65HVD78 also support this functionality. 

    Regards,

    Eric