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TCA9539: What's the difference between TCA9539 and TCA9555?

Part Number: TCA9539
Other Parts Discussed in Thread: TCA9555

HI team,

What's the detailed difference between TCA9539 and TCA9555? 

What's the output voltage level at default(power up but no input signal) for each device respectively? Are they output low level at default?


  • Hey Ted,

    The difference is TCA9555 has internal pull up resistors on its I/Os (weak pull up to Vcc and all inputs upon power up) while the TCA9539 does not (floating Hi-Z input upon power up).

    "Are they output low level at default?"

    No, both power up as inputs.