Other Parts Discussed in Thread: PCA9555
We have a PCA9555 that brings down the I2C network when it's temperature is above 60C.
Our circuit powers up the master device while the PCA9555 is powered off momentarily (the power sequencing brings up the PCA9555 after the master).
This is fine until the PCA9555 is warmed up (not past 85C). What we've observed is that the PCA9555 is pulling down down the SDA pin to 1.4V (normally 2.8V). If you hit the PCA9555 with coldspray and power cycle, everything is fine.
The PCA9555 is powered by 3.3V. The master I2C device operates at 2.8V. Both have common ground returns. Pull up resistors are near the master (
Any ideas? Thanks
Steve
