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MAX3221: MAX3221CPWR DIAGRAM

Martin Holguin
Intellectual 290 points
Part Number: MAX3221

Hello everyone,


I want to make a UART - RS232 interface with a 3.3V microcontroller and a MAX3221CPWR, the thing is that I have some doubts with the circuit I made, is this correct or is there an error:

I use MLCC 0805 capacitors, I suppose the DC bias effect should not be a problem or do you recommend me to use electrolytic capacitors?

  • +1
    Guru 270720 points

    There must be a bypass capacitor at VCC.

    Due to their lower ESR, ceramic capacitors work better than electrolytic ones with a charge pump. This is an old device that was designed when electrolytic capacitors with loose tolerances were common; if the DC bias effects are much worse than that, consider choosing a larger package.

  • 0
    TI__Mastermind 46427 points

    Hi Martin,

    Clemens is correct - there needs to be a bypass capacitor at Vcc.

    Also as Clemens mentioned as well - ceramic capacitors are generally the best fit for the charge pump pins.

    Please let me know if you have nay other questions! 

    Best,

    Parker Dodson