• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 34 subscribers
  • Views 212 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

PCA9535: PCA9535 keeps I2C line busy at HOT temperature

Jessica Ballard
Prodigy 20 points
Part Number: PCA9535


When bringing up the PCB that has 3 PCA9535's populated to appx 60C, I am noticing that the I2C line is being driven low before my MCU (master) attempts to communicate with the device. 

The MCU is located outside the temperature chamber, so I know it is isolated to the ICs on the board. I have powered off the other ICs that share the line and still seeing this behavior. Once I bring the temperature back down to appx 25C, I no longer see this problem. This is also not an issue at -40C. It looks like the PCA9535 are still operating, as the GPOs are configured before the temperature cycling and they are still outputting 5V. 

Not sure if this is a known problem or why there is a temperature dependency here.  

  • 0
    TI__Guru 50208 points

    Hi Jessica,

    Have you been able to determine if all three devices exhibit this behavior at 60C, or does it seem like only one device is affected? Do you have a way to only apply 60C to one IC at one time via thermal stream? 

    Can we try replacing one unit at a time with new PCA9535 silicon to see if the issue persists after each device change? I.e. change out device 1 on PCB for new PCA9535. Test board under temp. Replace device 2 for new PCA9535.... 3, repeat and see if the tests provide the same result. This would be similar to an ABA swap-like test. 

    As of now, not a known issue to me in my 2 years of supporting the device. I don't know of any temperature dependent issues. This device I believe is rated up to 85C with no problems. 

    Regards,

    Tyler