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TCA9539-Q1: question about Internal Read Pulse Fequency

Part Number: TCA9539-Q1
Other Parts Discussed in Thread: TCA9539, TCAL9539

Hi TI,

For TC9539-Q1, What is the frequency of the  Internal Read Pulse, and what is the minmum pulse width of I/O port to ensure signal flip can be sampled?



  • This device does not have any internal oscillator. The read pulse is derived from the I²C clock, and is generated once for every I²C read transaction, so its frequency is very low.

    The input data setup/hold times are specified in section 6.8 as 150 ns and 1 µs.

  • Hi Junsong,

    The TCA9539 does not latch the INT pin. If an input changes state and then changes back to the original state, the INT can be lost if you do not read it before the change back occurs.

    If I remember correctly, there is some sort of "high frequency" filter in the input path that is in the range of ~5MHz or so. We don't spec this in the datasheet so we don't technically ensure that the filter is accurately set around that frequency point. 

    If you are looking for a device that does latch the INT, I would suggest TCAL9539.