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TCA9539-Q1: TCA9539 output default output state

Scarlett Cao
Expert 3810 points
Part Number: TCA9539-Q1

Tool/software:

Hi team,

Customer is using TCA9539-Q1 for output channel expansion. they want to know when TCA9539-Q1 1) nreset pin low and 2) first power up, what the default output state, pull high or low?

Thanks

Scarlett

  • 0
    TI__Mastermind 36463 points

    Hi Scarlett,

    The TCA9539-Q1 always powers up with a default state resulting in all IO's configured to high-z inputs. It is best to tie a PU or PD resistor to these pins to keep them from floating or immediately configured them to some output configuration. 

    Regards,

    Tyler

  • 0 in reply to Tyler Townsend
    TI__Expert 3810 points

    Hi Tyler,

     I see datasheet output default state is 1, does the 1 means high Z?

    Thanks

    Scarlett

  • 0 in reply to Scarlett Cao
    TI__Mastermind 36463 points

    Hi Scarlett,

    The configuration register controls whether the IO is configured as an input or as an output. 

    The output port registers 0/1 control whether a pin configured as output is either HIGH or LOW. The default is 0xFF which means all outputs would output HIGH logic if the pins were configured as an output through register 0x06 and 0x07. 

    Since the default state of the configuration registers are 0xFF, all pins are configured to high-z inputs. 

    Regards,

    Tyler