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TLC59581: Power on unwanted row issue

Tristan Reimann
Prodigy 140 points
Part Number: TLC59581

Dear Sir,

We use TLC59581 driver and observe that when power on the circuit and displaying a black image, there are some rows that are turned on until an image no black is set ("or touch)" to the row that have this effect.If we enable the power save mode, this unwanted row disaper, assuming because the driver is going in save mode, but if we set not a black image but just low code of green for example, the effect is there since the power save mode doesn't occurs anymore. the phenomena doesn't occur at each power on.

It looks like as the driver has a current set in one of the output and keep it even when refershing the memory until a large code is set to this memory position.

We are still debuging this issue internally but if you have input to give us it is welcomed.

BR

Tristan

  • 0
    TI__Genius 14295 points
    Hi, Tristan,

    Could you first check if you are referring to or following the steps of the following note:
    www.ti.com/.../slva744.pdf

    Thanks.
    Regards,
    Kenneth
  • 0 in reply to Kenneth Du
    Prodigy 140 points

    Hi Kenneth,

    We have re-checked the link you send and it looks that we follow it in our implementation.

    The abnormality occurs just after we set the FC2 register, for a good output the node becomes floating after FC2 settings
    and the LED then is still off and for a no good output, we observe that the output node is driven low turning on the LED.

    This state occurs until we write a no 0 code into the memory of the concerned output.

    In the plots we can see the register initialization (with zoom) followed by the first memory bank data writing,
    and then the second memory bank where GCLK start to display first bank data. We write a black image (code 0)

    The FC1/2 register settings are:

    FC1 : 1001 000 111111111 010110000 010011000 0 000 0 0 000 1 00 01

    FC2 : 0110 00 00 00 00 00 00 0000 0100 0110 1 00 00 0 000 000 1 0 0 11111

    We have played with different settings but doesn’t look to change the phenomena,

    For reminder the phenomena does't occur at each power on but when an output has this issue
    there is high probability that it occurs often.

    Good output:

    No good ouput

    Best regards,

    Tristan