PCA9539: Data transition timing

Hello Yuto-san,

"Our customer want to switch 16-bit at the same time. Is it possible?"

Unfortunately not.

"If we read the data sheet, we can understand that it switches each 8 bits."

Thats correct. The device will update its ports (meaning 8 bits) at a time and during the rising ACK pulse of a write. This is shown in figure 15 under the write mode where you can see tpv shown.

May I ask what application you are working on in which you need all 16 bits to change at the exact same time?

-Bobby

Hi Bobb-san,

I'm confirming the application.

I'm sorry, there was a lack of explanation.
Do the output statuses of P00 to 07 and P10 to 17 switch at the same time?

Best regards,
Yuto Sakai

Hi Max-san,

Thank you for your reply.
Is "P01" wrong? Is it P00 correctly? Or is it P10?
If "P10" is correct, isn't the output status of P00 to 07 and P10 to 17 switched at the same time?
Even if the write timings are different, it is expected that the output statuses switch at the same time.

Best regards,
Yuto Sakai

Hello Yuto-san,

"Is "P01" wrong? Is it P00 correctly? Or is it P10?"

There is a typo in Max's reply: '......while P01 to P17....' P01 is meant to be P10

"Even if the write timings are different, it is expected that the output statuses switch at the same time."

No, our device will change P00-P07 (8 bits all at a time) and P10-P17 (8 bits all at a time). But not all 16 bits all at the same time.

-Bobby

Hi Bobby-san,

Thank you foryour reply.
Could you tell me which devices can switch 16bit at the same time?

Best regards,
Yuto Sakai

Hey Yuto-san,

We don't have any I2C devices which can switch more than 8 bits at a time. This might be something you have to find a SPI protocol device (I'm not aware of one from TI though).

-Bobby