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PCF8575 크랙: [PCF8575 ]If there is a default pull-down resistor in output mode

Lee HyungTae
Prodigy 10 points
Part Number: PCF8575
Other Parts Discussed in Thread: TCA9535, PCA9535

VCC 3.3V 입력, 포트는 출력 모드로 사용 중이다.
출력 라인에 기본 풀다운 저항(10Kohm)이 있는 경우 높은 출력 레벨은 3.3V가 아닌 약 2V 레벨로 출력됩니다.
무엇이 문제일까요?

  • 0
    Guru 317370 points

    The PCF does not have input or output modes. The port pins are "quasi bidirectional", that is, they can strongly pull low, but only weakly pull high. This is done so that a pin that is configured as high can be used as an input.

    If you want pins that are strong enough to overcome a pull-down resistor, use the PCA9535/TCA9535 (with different registers).