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SN65C3221E - hotswap application

Ryuji
Guru 20090 points
Other Parts Discussed in Thread: SN65C3221E

Hello,

I have some questions about SN65C3221E

(1)
Can we use SN65C3221E with hotswap application?

(2)
After hotswapping, 
The DOUT pin was not operated( fixed -1.7V) when connected the Load to DOUT.
Also the DOUT  pin was operated when remove the Load.
Could you please let me know possibility causes ?

(3)
Is the DOUT voltage varied when we connect difference load on the DOUT pin?
I understood that the DOUT voltage is varied on difference current(difference load).
Could you please let me know the caluculation for DOUT voltage with load?

Best Regards,
Ryuji Asaka

  • 0
    TI__Guru*** 147906 points
    Ryuji san,

    1) Yes the RS232 connector can be plugged or unplugged at any time. However it is best if the ground makes first connection which is the case when the connectors are have grounded DB9 (DE9) shells.

    2) DOUT should be over +/-5V into a standard RS232 receiver load which is 3k to 7k resistance to ground. If a DOUT line is connected to another driver output then the voltage could be -1.7V.

    3) The driver curves depend on VCC value. However they are same up to -5mA at about -5.3V

    For best ESD protection the SN65C3221E ground pin should have a wide trace with multiple vias to ground placed as close to the DUT pin as possible.
  • 0 in reply to Ron Michallick
    Guru 20090 points
    Hello Ron san,

    Thank you for the reply.
    I need your help again.
    Since I have some confidential information of customer I will send to e-mail. I know your e-mail.

    Best Regards,
    Ryuji Asaka