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MAX3243E: leakage issue on no power status

dimitry chen
Expert 1155 points
Part Number: MAX3243E
Other Parts Discussed in Thread: MAX3243

HI

When my whole device is no powered , and MAX3243 all pin (include DIN, FORCEOFF, FORCEON) are floating,

but there is a 10V(or there voltage) on RS-232 Input/ output pin,

is possible cause vcc or any pin become abnormal ???

, like 3V on VCC , some pins become on certain voltage level.

  • 0
    TI__Mastermind 25705 points

    Dimitry,

    There is a charge pump circuitry in MAX3243, which generate 2x Vcc voltage internally. You can find more details in this blog. If you see some voltages from the RS-232 pins, they must come from a supply. Could you check if the device is truly not powered? A good indicator is V+ or V- pins. If the charge pump works, V+/V- shows some voltage above/below Vcc. Please let me know if you have more questions.

    Regards,

    Hao

  • 0 in reply to Hao L
    Expert 1155 points

    hI

    thanks your information

    If my user scenario  is "other connected device sent output voltage" on my RS-232 Input/ output pin,

    is possible cause vcc or any pin become abnormal ???

  • 0 in reply to dimitry chen
    TI__Mastermind 25705 points

    Dimitry,

    I don't think the device should be back powered through RS-232 pins (Dout or Rin). Din and Rout pins are TTL logic. Can you help check which exact pin generate the issue? You can leave other pins open (except Vcc and GND) to do the test. As you mentioned, Vcc is unpowered. Thanks,

    Hao