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  • TI Thinks Resolved

OPT3101: Phase Out Of Range

Prodigy 70 points

Replies: 3

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Part Number: OPT3101

Hi Alex,

Here's my next question for you. :-)

I'm now watching that the phase is between 0 and 64000 as is done in the Latte EVM program. What I'm finding is that the phase values of one of the current ranges (TX1, HDR 0) is generally very high and moves to be greater than 64000 at one end of that range.

What influences this and what should I be investigating/adjusting to get phase readings within the acceptable range? I'm not finding any discussion of this in the docs, but may be missing it.
This is for a design using Super-HDR mode and with a set of register values generated from the configurator tool as the starting point.

Thanks,
Matt

  • Hi Matt,

    To confirm HDR0 is ILLUM_DAC_L for you correct? So this would be the second largest current setting. In what scenario does this happen? When you say end of the range is this the near or far end of the range?

    Best,

    Alex

  • In reply to Alex Bhandari-Young:

    Yep, that is what I mean. This is happening in the second highest current range.

    The settings I'm playing with are:

    HDR ratio is 48, LED current set to the max (173.6 mA). That yields (from the configuration tool):

    this->reg.illum_dac_h_tx0 = 3; // //High Current settings [012.6mA:4.2mA X 03]
    this->reg.illum_scale_h_tx0 = 1; // //Illum scale for H [012.6mA:4.2mA X 03]

    this->reg.illum_dac_l_tx0 = 3; // //High Current settings [004.2mA:1.4mA X 03]
    this->reg.illum_scale_l_tx0 = 3; // //Illum scale for H [004.2mA:1.4mA X 03]

    this->reg.illum_dac_h_tx1 = 31; // //High Current settings [173.6mA:5.6mA X 31]
    this->reg.illum_scale_h_tx1 = 0; // //Illum scale for H [173.6mA:5.6mA X 31]

    this->reg.illum_dac_l_tx1 = 17; // //High Current settings [047.6mA:2.8mA X 17]
    this->reg.illum_scale_l_tx1 = 2; // //Illum scale for H [047.6mA:2.8mA X 17]
    Best regards,
    Matt
  • In reply to Matt McFadden:

    Hi Matt,

    Didn't see an answer to the other question. When you say end of the range is this the near or far end of the range?

    If it is close end of range then this would be the wrap around i described where -1 will show up at the max phase setting. Since this only requires the phase to be off by one LSB less than zero. Is this what you are seeing?

    If far end it is possible that the crosstalk happens to have this angle. I have not seen this before - but may be able to correct by using the amplitude to differentiate if that is the case.

    Best,

    Alex

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