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TCA9539-Q1: Interrupt pin

Jules Wacquez
Prodigy 60 points

Part Number: TCA9539-Q1
Other Parts Discussed in Thread: TCA9539

Hello,

I want to connect multiple INT (each from one TCA9539) to the same line due to lack on of available pin on my micro-controller. Each TCA9539 is supplied by its own power supply, which can be turned ON or OFF. There is on pull-up resistor for the whole INT line, on an independent power supply.
My question is: "Is there an internal connection between the VCC pin and the INT pin (e.g. protecting diodes, … )?" , i.e. will shutting down one TCA9539 (connecting its VCC to GND) pull down the whole INT line to GND?

Best regards, 

Jules

  • 0
    TI__Guru* 79531 points

    Hey Jules,

    The INT pin for these devices are open drain. This means the only diode is from the body substrate of the NFETs. The body is terminated to the GND pin so the body diode goes from GND to the drain (INT PIN). This makes it impossible for you to conduct this diode unless you drive the INT pin below GND. The only other diodes are from an ESD cell which do not conduct unless you drive the INT pin above ~7V. You shouldn't have any problems with your application in terms of back biasing a diode or latching the INT line low due to biasing Vcc to GND. The pins are also 5V tolerant so they can handle voltage even when no Vcc is present.

    Let me know if you have any further questions,

    -Bobby

  • 0 in reply to BOBBY
    Prodigy 60 points

    Thank you very much for this answer.

    -Jules