Part Number:TCA9535
My have a military customer who is having an issue with the TCA9535TWR at -40C. Here is a description of what the customer is seeing:
I performed some tests with a known good board as well as a problem board. Our configuration uses a TI MSP430x2xx micro controller communicating with the TCA9535TWR I2C expander on the I2C bus. Our software waits 10 msec after power on before attempting communication with the I2C expander. After the 10 msec delay, the microcontroller looks at the UCBBUSY bit on the UCB0STAT register to determine if the I2C bus is busy or idle prior to attempting to access the I2C expander.
For the known good board, 10 msec is enough delay after power up for the I2C bus to come back as idle at both room temperature (25 degrees C), and at -40 degrees C. For the problem board, 10 msec is sufficient at room temperature for the bus to come back as idle, but at -40 degrees C, we had to increase the delay to 100 sec in order for the bus tom come back as idle.
The delay in the bus becoming active seems to be excessive to me. Have you seen this issue before?
Do you need to see any of the design details or layout? It might be difficult to get this considering that this is military customer, but I can try.
Please let me know if you have any further questions.
Richard Elmquist