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DLPC3479: Trigger In timing rules

Kazuo Hayashi
Prodigy 40 points
Part Number: DLPC3479

What are the timing constraints required for TRIG_IN?

The figure below is taken from the DLPC3479 datasheet, with T1 and T2 added.

In the figure, it is not clear at what timing Trigger In (TRIG_IN) should be input to display Pat1 and after.

・Are there any timing constraints on T1? (For example  T1 > Tdarkpost)

・Is T2 always equal to Tdarkpre?

fig. 1

  • 0
    Prodigy 40 points

    I forgot to mention.

    Operation Mode : Internal pattern, Trigger in mode

  • 0 in reply to Kazuo Hayashi
    TI__Expert 5870 points

    Hello User,

    Thank you for your interest in DLP technology.

    When in Internal Pattern mode, in the Pattern Set Order page you get options for your Pre/ Exp/Post times. See image below.

    Your TriggerIn frequency should be the same as the total Pre/Exp/Post times listed in the table. In this example I have two patterns and each pattern take 5080 usec to be displayed properly. That requires that the TriggerIn must be be ~196 Hz (1/5080 usec). You may go lower than this frequency. A higher frequency may not allow for the system to load the pattern properly.

    Regards,

    John

  • 0 in reply to John McKnight
    Prodigy 40 points

    Thanks John.
    I understand about the frequency of TriggerIn.

    I believe that the period from the rising edge of TriggerIn to the falling edge of TriggerOut (end of display) is equal to PreDark+Exposure time.

    Hence, our firmware controlling TriggerIn waits PostDark time (+ additional margin) from the falling edge of TriggerOut2 (end of display) to start up TriggerIn.

    Is it safe to assume that the above method will keep the TriggerIn frequency below the required value?

  • +1 in reply to Kazuo Hayashi
    TI__Expert 5870 points

    Hello User,

    I believe that the period from the rising edge of TriggerIn to the falling edge of TriggerOut (end of display) is equal to PreDark+Exposure time.

    That would be correct if you are referring to TriggerOut as TriggerOut2.

    Is it safe to assume that the above method will keep the TriggerIn frequency below the required value?

    This should be fine. The external trigger needs to allow for the EVM to finish the post darktime process. It seems your method covers that issue.

    Regards,

    John