This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

  • TI Thinks Resolved

DLP4710: Using external illumination, external 3.3V for VCC_INTF, no need for 2.5V (?)

Prodigy 55 points

Replies: 17

Views: 185

Part Number: DLP4710

I have some questions about the DLPA3005 as used in a DLP4710+ 2X DLPC3439 design.  There's a schematic image below.

1. I will be using external illumination sources and timing circuitry (no color wheel, I just need 1-bit patterns sent to the DMD with no challenging timing requirements), so I don't need any illumination-related function from the DLPA3005: can I NC all the illumination-related pins as shown in the schematic below without causing issues?

2. I don't need a 2.5V source (e.g., PWR3_OUT DLP4710EVM eval board design): can I NC the PWR3-related pins as shown in the schematic below without causing issues?

3. I have an external 3.3V supply from the host that I had planned on using for VCC_INTF of the two DLPC3439 controller chips so I don't need to use any output of the DLPA3005 for this (e.g., PWR4_OUT as used in the DLP4710EVM eval board design): can I NC the PWR4-related pins as shown in the schematic below without causing issues?

3a. This external 3.3V source will be on "all the time" with respect to the DMD-related ICs (even when, for example, PROJ_ON from the host is low): will this cause issues?

3c. I can use the DLPA3005A PWR4 for the VCC_INTF is that makes this lower risk, it's just the minor additional components and complexity I am trying to avoid.

Thanks.

  • Andrew,

    Thanks for your interest in our DLP technology. Here are some initial comments from me:

    > The DLPA3005 checks the illuminator connections upon boot, and refuses to boot if one of its three RGB LEDs is not connected/detected. What does your external illumination setup look like?

    > PWR4_OUT and PWR3_OUT should have capacitors on the output even they are not being used in the board design.

    Let me know what information you can share about your illuminator configuration so we can assist you further.

    Regards,

    Philippe Dollo

    If a post answers your question, please click the "Verify Answer" button.

  • In reply to Philippe Dollo:

    Philippe,

    Thanks for the details, I added a 1 µF from PWR4_OUT to GND and the same for PWR3_OUT.

    I am using a single white LED for illumination as opposed to three RGB LEDs.  The LED can draw up to 40 amps continuously (sometimes we pulse to higher), so it's beyond what the DLPA3005 can provide. 

    Does the 3005 check for some amount of current going through the sense resistor after toggling the FETs to see if the LEDs are present??  Maybe I could wire all three high side gate driver pins to the high side of the sense resistor?  Maybe need a tri-state buffer on each pin if the voltage from an inactive pin would damage the high side driver of the inactive pins or if we need to deliver more current than the high side driver pins can push?

  • In reply to Andrew McFarland:

    Andrew,

    We are looking into your queries and will get back to you soon.

    Regards,

    Mayank

  • In reply to Mayank Khandelwal:

    Any update on this?

    Thanks.

  • In reply to Mayank Khandelwal:

    Andrew, 

    Yes, there is a check in the initialization process which checks whether LEDs are connected or not. If you are planning to use an external LED driver then you will have to use a firmware in which this check will be bypassed. Let us know if you require this modified firmware in which we will disconnect all the LED connections.

    Correction (by Vivek) :

    The requested features for external LED driver is supported by the Light Control chip-set (DLPC3479) + DMD4710LC DMD.  This feature is not supported on the Display chip set DLPC3439 + DLP4710 DMD. 

    Regards,

    Mayank

  • In reply to Mayank Khandelwal:

    Hello Mayank

    Is it possible to don't use this DLPA3005 if we use the modified firmware? I want to use a MCU to control the LEDs.

    I use TPS65145RGER for DMD voltages and use LED sel for syncing.

  • In reply to Morteza Ozlati:

    Hi Morteza,

    Only DLPA3005 ensures the required controller and DMD power-sequences. TI doesn't allow or provide firmware to drive LED and DMD with external power supply designs; also ensure DMD reliable operation 

    Regards,

    Sanjeev

    If a post answers your question, please click on "Verify Answer" button

  • In reply to Sanjeev:

    Hi Sanjeev, 

    I am JJ, working with Morteza on the same project using the DLPC3478/DLP3010. 

    What we actually want is the modified firmware that bypass the checking whether the LEDs are connected or not. It is for our evaluation purpose.

    One thing I would like to ask regarding the modified firmware is that the LED signals such as the enable and PWM still functioning?

    Thanks!

    Best Regards,

    JJ

  • In reply to Joo Jie Ho:

    Hello JJ,

    I am looking into your queries and will get back to you in a day.

    Regards,

    Mayank

  • In reply to Mayank Khandelwal:

    Hi Mayank,

    Thanks. Looking forward for your reply on this.

    Best Regards,

    JJ 

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.