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DLP6500FLQ: Frequency of PWM

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Replies: 12

Views: 1887

Part Number: DLP6500FLQ

Hi,

Let me talk about DLPC900.

Please let me know frequency of PWM from BLU_LED_PWM,GRN_LED_PWM,RED_LED_PWM.

The modify of duty is described in Table 2-64. LED Driver Current Command Definition of Programmerd Guide.

But I do not see frequency.

Best regards
Hiroyasu

  • Hi,

    Could you reply??

    Best Regards
    Hiroyasu
  • In reply to Hiroyasu Tazawa1:

    Hello Hiroyasu-san,

    Please accept my apology, I answered this the day it came, but apparently it did not post correctly.

    The frequency of these PWM signals is ~18 kHz. This gives 1024 steps.

    Fizix
  • In reply to Fizix:

    Hi, Fizix-san

    Thank you for your reply !

    I got upto 18kHz of PWM frequency,
    But  I want to make sure about 1024 steps.

    I read DLPC900 Programmers Guide.

    Control of Duty cycle are described in Section 2.3.5.2 LED Driver Current.
    and It mention that User can control 256 step(8bit).

    Which is correct ??
    Please let me know, if I read wrong section for control.

    Best Regards
    Hiroyasu

  • In reply to Hiroyasu Tazawa1:

    Hello Hiroyasu-san,

    I am sorry for the confusion. The 18 kHz can give up to 1024 steps, but the implementation in this firmware/API is 256 steps.

    I hope this helps.

    Fizix
  • In reply to Fizix:

    Hi, Fizix-san

    Thank you for your support !!
    I got it.

    Best Regards
    Hiroyasu

  • In reply to Fizix:

    Hi,

    Sorry I have a favor,
    Can you tell where 18kHz is described in Datasheet ?

    and Sorry, I have a misstake,
    Setup of duty cycles is desciribed in 2.3.5.2 LED Driver Current.
    But I do not see how to set up frequency ?
    I can not found in Programmers guide.
    Can you tell me this command in Programmers guide.

    Best Regards
    Hiroyasu
  • In reply to Hiroyasu Tazawa1:

    Hiroyasu-san,

    It is not in the Programmers Guide and in the implementation of the DLPC900 firmware, the frequency is fixed.

    I have not measured it, but the default for the ASIC is 18.2 KHz. I have put a ticket in to see if maybe the next firmware/GUI version can expose this setting.

    Fizix
  • In reply to Fizix:

    Hi, Fizix

    Thank you for your reply.
    Ca you confirm Frequency of BLU_LED_PWM,GRN_LED_PWM,RED_LED_PWM are 18.2kHz, right?
    Because my customer measure these PWM, and it was about 74kHz...

    Best Regards
    Hiroyasu
  • In reply to Hiroyasu Tazawa1:

    Hello again Hiroyasu-san,

    After seeing this message, further digging and consultation with the engineer that designed the firmware revealed that although the default frequency is 18.3 kHz the steps were limited to 256 by increasing the frequency by 4x.  This yields 73.2 kHz, so that 1024 steps becomes 1024 ÷ 4 = 256 since the minimum pulse width is 53.3 ns.

    There are currently no plans to change or expose the number of steps and expose frequency control, but we are discussing the possibility internally as a result of your inquiry.

    I am sorry for the confusion about the firmware implementation.

    Fizix

  • In reply to Fizix:

    Hi, Fizix

    I want to confirm this,
    I understand Output of PWM is 73.2kHz and User can not change this value.

    Is this understanding correct ??

    Best Regards
    Hiroyasu

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