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CDCE913: I2C, onboard programming and 3.3V

Vitaly And
Prodigy 180 points
Other Parts Discussed in Thread: CDCE913, CLOCKPRO, PCA9306

Hello,

we have issues while programming CDCE913 onboard. We use 913PERF board and ClockPro software. According to the datasheet for 913PERF we connect SDA and SCL lines to our board's dedicated header.

The SDA and SCL lines are pulled up on our board to 3.3V through a 3.3k resistors. We have a CPU on this I2C bus to control CDCE913. The CPU is also clocked via CDCE913, so there is not possible to program the CDCE913 initially via CPU, we use 913PERF instead for first launch.

One year ago we build a few prototypes, all works fine, But now we cannot access the CDCE913.

The setup is only working with disconnected 3.3v pullup (high level is done via 10k pullup to 1.8V on 913PERF). Also replacing the old 3.3k to something like 43k helps but the rising edge timing is very bad in this case.

The CDCE913 datasheet says that the I2C pins are 3.3V-tolerant. What can be a cause of the issue otherwise?

  • 0
    TI__Genius 10320 points
    Hi Vitaly,

    Someone on our team is looking at your request and will get back to you shortly.

    Thanks!

    Gabe
  • 0 in reply to Gabe Ayala
    Prodigy 180 points
    Today we replaced the PCA9306 level shifter in 913PERF board. This does not help. It works somewhat better but the stabililty is very bad.
    We have buit an own programmer based on atmel MCU and it works fine without any 1.8 V voltage.
    The only cause of the issue is thererfore the PCA9306.
    Early we also tried to work completely without the shifter, and also without success. I will try again to deinstall the PCA9306 in order to confirm the above conclusion.
  • 0 in reply to Vitaly And
    Prodigy 180 points
    And yes, removing the PCA9306 helps.
    Here is the solution:
    1. Deinstall PCA9306
    2. Short the pads 3-6 and 4-5 on PCB.
    3. Remove R58 and R57.
    4. Connect to board according to the manual.