PCA9538: Default output values

McKenna Strambi

Part Number: PCA9538

Tool/software:

Hi team,

Wanted to clarify what the default output is on reset? I see this on the datasheet and want to make sure this is the right thing to look at:

Additionally, is it possible to get rid of the 1M pulldowns if default after reset is 0V outputs or inputs with pull downs to GND. See schematic capture below.

Thank you!

McKenna

over 1 year ago

0 Clemens Ladisch over 1 year ago

Guru 320660 points

After a reset, all pins are configured as inputs (without pull-up/-down). If you want the outputs to be low before the I²C master has configured the PCA9538, then you need pull-down resistors.

(To ensure that the outputs do not drive high, initialize the output register before the configuration register.)

0 Tyler Townsend over 1 year ago

TI__Guru 56588 points

Hi McKenna,

I agree with Clemens here. Please let me know if you have any more questions.

Regards,

Tyler

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PCA9538: Default output values