TCA9539: TCA9539RTWR output status

Lisa Xu

Part Number: TCA9539

Tool/software:

Dear TI Team:

I just want to check IO expander_TCA9539RTWR output status.

When one Port of TCA9539RTWR is set to output, it will have 3 status: High,low, and High impedance, Right?

Best Regards

Lisa

+1 Clemens Ladisch 9 months ago

Guru 317280 points

A pin that is configured as output will drive either high or low.
If you want a high-impedance pin, you have to configure it as input.

0 Tyler Townsend 9 months ago

Hi Lisa,

I agree with Clemens here. Please see his response on the output state.

Regards,

Tyler

0 Lisa Xu 9 months ago in reply to Tyler Townsend

Hi Tyler,Clemens:

Got your points.mostly IC just has two status when set to output, but I saw some will support high impedance(high & low mosfet both off).

And check from the block diagram of TCA9539RTWR, I assume it will also have status with both Q1 & Q2 off when set to output.

Lisa

0 Clemens Ladisch 9 months ago in reply to Lisa Xu

Guru 317280 points

When the pin is configured as input, the configuration register's Q output is high and /Q is low, so Q1 and Q2 are off.

+1 Tyler Townsend 9 months ago in reply to Lisa Xu

Hi Lisa,

When the I/O pin is configured to be an OUTPUT, either Q1 or Q2 will be turned ON depending on the values in the output port register (0x02 & 0x03).

If you desire the I/O pin to have Q1 and Q2 disable, configure the I/O pin to be a high-z input through the configuration registers (0x06 & 0x07).

Regards,

Tyler

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