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MAX3237EI

Haim Rodrik
Intellectual 350 points
Other Parts Discussed in Thread: MAX3237E

Dear Colleges,

I have 4 different prototype boards, (4 different projects), different VCC's 3.3V, 3.9V, 4.3V and 5V. The common IC for all 4 projects its MAX3237EI. years ago 99% similar use for the MAX3237 and the boards work very good. Now I used TI in first time as a substituted nothing works.

I connected :

  • Pin 14 - SHUTDOWN to VCC
  • Pin 13 - EN to GND
  • Pin 15 - MBAUD to GND

Nothing happened.

All the unit works but the MAX IC.

Need help urgent

Thanks

Haim Rodrik

  • 0
    Intellectual 350 points

    Note : The capacitors that I tried some boards are 0.1uF and some of them 0.22uF values.

    Haim Rodrik

  • 0 in reply to Haim Rodrik
    TI__Guru**** 164606 points

    Haim,

    By nothing works, do you mean that all DOUT and ROUT pins are 0V and do not change with DIN and RIN?  
    What is the voltage on V+ and V- pins?

  • 0 in reply to Ron Michallick
    Intellectual 350 points

    Ron,

    I mean not working , I am connecting to PC+ Hyper-terminal  and there is no response. I have special jumper for board test when its connected instead the modem i have characters echoed back so I know if the Interface cicuit works as needed.

    the voltages as you request :

    • VCC    3.3V
    • Pin27  5.95
    • Pin4    -5.63

    I will check later in other boards that VCC there its 5V, 3.9V, 4.3V

    Thanks

    Haim Rodrik

  • 0 in reply to Ron Michallick
    Intellectual 350 points

    Ron,

    I measured pin outs RS232 level of DB9 connector

    • DCD    -5.63V
    • DSR    +5.95V
    • TX         -5.63V
    • RTS      0V
    • RX        0V
    • CTS     +5.95V
    • DTR    0V
    • RI        5.63V

    Thanks

    Haim

  • 0 in reply to Haim Rodrik
    TI__Guru**** 164606 points

    Haim,

    The MAX3237E is supplying a signal to the five powered DB9 lines.
    However, there is no voltage on the three lines that come form the remote RS232 port.

    Double check the connections and possible need for null modem cable (reverses RX/TX and other control lines).

  • 0 in reply to Ron Michallick
    Intellectual 350 points

    Hi,

    When I connect the cable all pins have voltage. The measurement above was without serial cable. I double check each pin direction and wiring , G24 modem pin out, MAX3237EI pin out, board DB9 pin out and PC DB9 pin out , there is no mistake with wiring and and data flow direction. I took the G24 modem on evaluation board the serial communication works with same PC and Hyper-terminal. The only problem focused on MAX3237EI chip. We are going to loose the order because its took long time and no time to manufacture new design or use other chip-set. I can send the drawing for review. I have brand new 60 proto boards, I have the same problem  on all boards.

    If the client will cancel the order big loose for us.

    Thanks

    Haim Rodrik

  • 0 in reply to Haim Rodrik
    TI__Guru**** 164606 points

    Haim,

    I see all pin has voltage when connceted. This is good.

    For PC terminal program to send data the remote RS232 device (MAX3237) must set handshaking lines properly.
    For PC terminal program to receive data the remote RS232 device (MAX3237) send data when allowed by PC.
    The UART and software handles this.

    If DOUT is not inverted DIN or ROUT is not inverted RIN, then MAX3237 may be the problem, otherwise the problem is somewhere else.