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About TRSF3221E circuit

Nat Wong
Genius 3070 points
Other Parts Discussed in Thread: TRSF3221E

Dear Sirs

My customer uses TRSF3221E.

And they want use TXRX_EN to choose TX function or RX function.

The circuit is shown as follow.

Is any concern about the circuit? THanks~

BRS

Nat

  • 0
    TI__Guru*** 140136 points
    Nat,

    Please use capacitors listed in table on page 12 of data sheet for 5V VCC operation.

    Schematic is not correct. Pin 1 can remain low. This pin only affects ROUT pin.
    TXRX_EN should go the FORCEOFF and FORCEON pins.

    TXRX_EN low will disable DOUT so COM1 pin can be driven from an external RS232 signal and the received signal can be read from ROUT.
    TXRX_EN high will enable charge pump then DOUT (after about 100uS) so COM1 pin will be at DOUT level set by DIN. ROUT will track DIN. Note that the driver will power two RS232 loads, the local 5k of RIN and the remote 5k resistor. Therefore DOUT may be a little less than +/-5V.

    The invalid output will be useful to tell if the COM1 line is active or not.
  • 0 in reply to Ron Michallick
    Genius 3070 points

    Dear Sirs

    Thank you for your great support.

    I modify my circuit as follow:

    Do you have any suggestion about th circuit?

    I do two function: Driver and Receive by setting pin EN,FORCEOFF and FORCEON.

    A:Driver

    EN is set to high.

    FORCEOFF is set to high.

    FORCEON is set to high or low.

    If I do not need "VALID RIN RS-232 LEVEL" function,

    May I set  FORCEON to high?

    B:Receive

    FORCEOFF is set to low.=>DOUT Z

    EN is set to low.

    BRS

    Nat

  • 0 in reply to Nat Wong
    TI__Guru*** 140136 points

    Nat,


    You may connect EN, FORCEON, and FORCEOFF together as a single control line.

    Do not leave FORCEON as always low.