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TLC59108 IREF problem

Steve Bragg
Prodigy 20 points
Other Parts Discussed in Thread: TLC59108, TLC59116F

Hi,

In the TLC59108 datasheet on page 17, it states that all bits of the IREF register are R/W and that the default value on power up is 0xFF. But when I check the default value, it's 0x9F. When I try to set IREF to 0xFF, I read IREF back as 0x9F. When I try to set IREF to 0x00, I read IREF back as 0x80. So it seems like bit 7 doesn't want to clear, and bits 5 and 6 don't want to set.

The I2C communication is running fine. I can turn on and off leds, and so far I haven't found any other problems. I've tested this issue on two separate boards and I'm getting the exact same result.

Has anyone else experienced the same issue?

Thanks,

Steve

  • 0
    TI__Guru 68125 points

    Hello Steve,

    Do you read and write register 0x11 or 0x12? Table 11 shows the wrong register number in the actual datasheet version.

    Best regards,
    Brigitte

  • 0 in reply to Brigitte
    Prodigy 20 points

    Hi Brigitte,

    Thanks for your reply. I did notice that Table 11 has some errors in it. I've been writing to address 0x12.

    The TLC59108 seems to work intermittently. I can get LEDs to turn fully on, but I can't use the individual led PWMs to control brightness. I'm also working with a TLC59116F, and it wont even ACK when I send it a slave address. Out of all the devices I have on the I2C bus, the only ones giving me trouble are the TI LED drivers. I think it may be time to try a different brand.

    I think if TI knows about errors in their datasheets, they should fix them as soon as possible. If I can't trust the datasheet, how can I trust that the part also works as advertised?

    Steve.

  • 0 in reply to Steve Bragg
    TI__Guru 68125 points

    Hello Steve,

    Other customers are using TLC59108 and TLC59116F without problems with the I2C interface. I wonder if there is maybe a timing issue at the input of the TLC591xx on your board. Is TLC591xx on your board maybe the last one in a row of I2C parts on your board?

    Whenever we find a inaccuracy or failure in our datasheets, we start a rework process of the individual datasheet to correct it. This is also the case with this one, but this process takes some time.

    Best regards,
    Brigitte