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DLPA3000: Internal connection on the Rlim_K and Rlim_BOT_K pins

Part Number: DLPA3000


The RLIM_1 and RLIM_2 are separated internally but is it the same for RLIM_K_1 / RLIM_K_2 and RLIM_BOT_K_1 / RLIM_BOT_K_2 ?

Can two different resistors be used to separate the "R MOSFET" channel from the "P MOSFET" channel and the "Q MOSFET" channel?    


  • Yoann,

    Welcome to the E2E forums, and thank you for your interest in our DLP technology.

    Each of the three channels above is controlling one of the three RGB LEDs driving the system's optical engine. The resistor you are pointing out here (25mOhm) is the Rlim resistor which is used to drive the IDAC with the correct current values. As such, changing this value will change the behavior of the IDAC. In typical use case, this Rlim resistor is increased if the user wishes to reduce the top end current (from 0 to 1023) of the IDAC.

    Given the above, it would not be recommended to use multiple resistors for each channel as the three channels would no longer be scaled the same for the same IDAC output value. Instead, it is recommended to tune the IDAC output values via I2C command in the DLPC343x controller to get the current output level you seek on each channel (see section 3.2.5 of DLPC343x Programmer's Guide ).

    Are you seeking to do anything different than this with your LEDs?


    Philippe Dollo

  • Thank you for your answer.

    In our application, we don't need to use RGB LEDs.
    We only use white LED. In some steps of DLPC343x process, we need to stop the white LED without disturbing the DLPC343x process in progress.

    We are thinking of adding an external command on the LED_SEL inputs of the DLPA3000. With this command, we will switch the LED channel to stop the white LED.
    We have a doubt that we will not disturb the DLPC343x if we switch to an open circuit (no current) LED channel.
    If we can use a different Rlim, we will use a higher resistor to reduce the current and limit the heat dissipation without disturbing the DLPC343x and DLPA3000.

    Do you think this is possible ?

  • Hello Yoann,

    Could you please share more details about your approach preferably  including a high level block diagram? This will hekp us answer your question.



  • Hi,

    For example, in this case, we considered using an external command to switch from P_Channel to R_Channel. We want to stop the LED without impacting the DLPC process, the DLPC continues to control the P_Channel.

    We want to use a higher resistor on R_Channel to reduce the heat when it's used.

    Other possibility considered

    Use the external control to turn off the LED, in this case we stop the power consumption on the LED channels of DLPA. But doesn't the DLPC detect this case?

    We don't want the DLPC to detect it and stop its process.

    Our goals, it's to use an external signal to stop the LED during the process of the DLPC without disturb it.

    Do you think this is possible?


  • Hi Yoann,


    I believe that it is possible to stop the LED using an external signal shutting down the DLP controller.

    It is recommended to use the DLPC343x controller to control the DLPA3000 process without the introduction of external signals, to avoid interference with normal operation. The block diagram and steps that follow will outline how this can be achieved. In this case, all LED Control Lines are the normal connections recommended in our reference designs:


     Example of DLP system with only one LED connected


    1. The firmware uploaded to the DLPC343x controller will need to be modified to allow the system to operate with only one LED connected. We can provide this firmware.

    2. Have the external system controller (i.e. front-end processor) send an i2c command to the DLPC343x controller. This can be achieved by consulting the dlpc343x software programmer’s guide; section 3.2.3 details the Write RGB LED Enable command (0x52h).

    3. The DLPC343x controller will process this request and communicate with the DLPA3000 PMIC to turn off/on the white LED (connected to R_channel).


    Is this a feasible solution on your end?

    Best regards,


  • Thanks for your answer.

    We will examine this possibility with my colleagues

  • Yoann,

    On Chris's behalf I can say that you are welcome.

    Please let us know how you would like to move forward when your team has discussed.