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DLPA2005 : External Cthode method of LED.

seonmin seong
Prodigy 20 points
Part Number: DLPA2005
Other Parts Discussed in Thread: DLPC3478

DLPA2005 is operated in the R, G, B of an LED are sequentially.

(Chipset : DLPC3478)

However, I need the condition that the LED can be operated simultaneously with G & B or R & B.
So, we are considering three options.
1. Using the Commmon Anode of DLPA2005 and trying to implement the Cathode by using an external FET.
    (The space for placing parts is small. So, I want to use DLPA2005.)
    Are there any precautions when using this way?
2. Common Anode of dlpa2005 is used, and only Cathode Path is separated to the outside.
    Are there any precautions when using this way?
    
3. DLPA2005 is used only as a DMD power configuration.
    LED's Anode and Cathode are externally configured.
    (If there is a product that can be referred to as an external Anode, please recommend it.)
    Currently, it is being confirmed as the DLPC4500.

※ LED EN Control is done in the External Chipset.
    Driving referring to TRIG1, TRIG2 of DLPC3478.

  • 0
    TI__Genius 9971 points

    Hello ,

    Welcome to TI E2E forums and thanks for showing interest in DLP technology.

    Unfortunately, the DLPC3478 chipset is capable of only sequential LED support. Hence it will not be possible to meet a condition where multiple LEDs are operated simultaneously.

    Regards,

    Mayank

  • 0 in reply to Mayank Khandelwal
    Prodigy 20 points

    Dear Mayank,

    I know that the DLPC3478 works sequentially.
    So, I want to implement it as mentioned above.
    It is to ask if there is any precaution.
    Or, have other companies considered the same method as mine?

    Regards,

    seong

  • 0 in reply to seonmin seong
    TI__Genius 9971 points

    Seong,

    Please refer to my comments below -

    It sounds like you would like to operate G&B and R&B simultaneously.  Based on the LED select lines the DLPA2005 drives the R, G, and B LED.  If you want to drive G and R at the same time then they will have to be connected to the same low side FET inhe DLPA2005.

    So option 1 wouldn’t give you the expected outcome. Also while connecting different LEDs with different VLED voltages to the same channel you won’t get the same current through both LEDs so the light output will be different.

    Option2: I assume the cathode is not connected to the DLPA2005 anymore. The DLPA2005 will stop driving VLED since there is no feedback anymore.

    Option 3:  Would work. Customers can use external LED drivers in combination with our PMICs to drive additional LEDs at the same time with our sequential LEDs. We don’t have a reference design for this and hence we don’t encourage customers taking this approach.

    I hope the above information answers your queries.

    Regards,

    Mayank