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TCA9539-Q1: input state change latch and interrupt output

Takuma Ito
Expert 5200 points
Part Number: TCA9539-Q1
Other Parts Discussed in Thread: TCA9539, , TCA8418E, TCA8418

hello 

I want to use this device to detect the activity on communication line. When the communication is not active, the line is fixed to low. when the communication started, the line will go high and low, continuously switching. The TCA9539's /INT will go low when the state of input pin changed, but it will also go high when the input pin state change back to original value. I want to latch this /INT low when the communication started. 

Is there any good idea to do this? any recommendation?

I will use remaining input port for DC level detection and send interrupt to MCU. 

  • 0
    TI__Guru 72551 points

    Hey Takumi-san,

    From what you are describing, our device would not work to tell you there was communication on the I2C line because it does not latch the INT, once SDA/SCL goes back to idle, the INT would de-asset. You would need to put a latch (maybe an SR latch) on the SDA/SCL line and feed the output to the TCA9539-Q1 in order for this to work.

    We do have one device which would latch the INT and that would be TCA8418/TCA8418E however that device is not automotive qualified. (Is auto-qualified a requirement for you?)

    Thanks,

    -Bobby

  • 0 in reply to BOBBY
    TI__Expert 5200 points

    thanks bobby ,

    Yes, I need Q1 grade for latch device. 

    Takuma 

  • 0 in reply to Takuma Ito
    TI__Guru 72551 points

    Hey Takuma,

    Unfortunately we do not have a Q1 grade device which latches the INT pin, it sounds like you would need a discrete solution.

    -Bobby