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SN65DSI83: SDA line keeps shorting to ground and schematic review.

Diego Minatto
Prodigy 20 points
Part Number: SN65DSI83

Tool/software:

Hello, i´m using a SN65DSI83 to interface a LVDS panel.

I´m running into a problem where the SDA pin on the bridge keeps getting internally shorted to ground, i soldered the chip to my board and then tried to do a I2C scan, it successfully returned 0x2C, but after some time i got no more response from it, checking the i2c bus SDA was pulled low, SCL was fine, i removed the chip and the bus returned to being pulled high by the resistors. It happened on two distinct IC´s, i have a level shifter to convert the I2C 3v3 signal from the controller to 1v8 on the SN65. I thought it maybe was connected wrong, but checked and the pins never see more than 1.810V.

I can´t find why the pin keeps shorting, so maybe something in my schematic is wrong ?, i was wondering if you guys could review my schematic to see if something there is wrong.

If not, what could cause the pin to short ?

The resistance on the pins from ground are:

SCL: 11.5M

SDA: 0,9M

3V3 Regulator:

1V8 Regulator:

SN65DSI83:

  • 0
    TI__Mastermind 22930 points

    Hi Diego,

    There is no known issue with the DSI83 I2C lines, so this could be related to the hardware implementation here. Do both the 1.8 V and 3.3 V rails have pullup resistors? 

    Is the I2C host controller pulling the bus down? Or is there any timeout happening on the bus from the controller side?


    Are you also testing the DSi83 with video and other chip functions such as receiving and outputting video are working correctly continuously? It would help to know whether other functions are not affected and only I2C is showing an issue.

    Best regards,
    Ikram

  • 0 in reply to Ikram Haque
    Prodigy 20 points

    Hello Ikram, yes both have pullups, i checked everything in the bus and the connector that leads to the processor has a bad contact. I gonna replace it but may take a few days. I also bought a few more samples of the DSI83 since the ones i had are dead. What do you think of my schematic ?, should i keep the way it is ? I still can´t figure out why both the DSI stopped answering the commands, even if i use a external micro controller to try to scan the bus it will not find it.