PCA9544A: I2C Timing-can PCA9544A support 0.6us for I2C start or repeated start condition setup time under standard mode 100kHz

Daniel Wang

Part Number: PCA9544A

Hi Team,

A customer has found the CPU's I2C timing at 100kHz can only get ~4.6us for Tsts :I2C start or repeated start condition setup time, less than 4.7us min from PCA9544A spec.

However, PCA9544A also support 0.6us min for 400kHz fast mode.

Supposing the I2C block cannot detect and switch to different I2C mode, the PCA9544A should be ok with 0.6us min for Tsts even with 100kHz standard mode.

So could you please comment if this is correct and if customer can go with ~4.6us and even 0.6us for Tsts during 100kHz I2C clocking？

over 2 years ago

0 Clemens Ladisch over 2 years ago

Guru 271800 points

This device indeed makes not difference between standard and fast modes.

These limits are copied from the I²C specification, and are listed only to prove that this device is compatible with other devices in these modes.

0 Eric Hackett over 2 years ago in reply to Clemens Ladisch

TI__Guru 68512 points

Daniel,

As Clemens said, this device adheres to the I2C specification, and does not adjust based on standard or fast mode. The physical layer design is capable of both modes and shows parameters from both to prove compliance.

Regards,

Eric Hackett

Interface

Interface forum

PCA9544A: I2C Timing-can PCA9544A support 0.6us for I2C start or repeated start condition setup time under standard mode 100kHz