TCA9539-Q1: TCA9539 output default output state

Scarlett Cao

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

10 months ago

0 Tyler Townsend 10 months ago

TI__Mastermind 49538 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 Scarlett Cao 10 months ago in reply to Tyler Townsend

TI__Expert 4040 points

Hi Tyler,

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

Thanks

Scarlett

0 Tyler Townsend 10 months ago in reply to Scarlett Cao

TI__Mastermind 49538 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

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TCA9539-Q1: TCA9539 output default output state