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TLC5957: LOD(LED Open Detection) function for TLC5957

Jongwoon Kwak
Prodigy 30 points

Part Number: TLC5957

I composed passive matrix driving system with TLC5957.

My panel board has passive matrix type LED arrays.

One of LED arrays has LED open cell. (And catapillar was not removed yet even though I have used TLC5957.)

As far as I know, During driving time, TLC5957 detect LED open cell automatically.

After TLC5957 detect open cell, Does TLC5957 do not give a output current on output pin? 

I mean that Is output current zero automatically whenever output pin meets open cell during driving period.

How can I know this LOD function is operating accurately. 

Is there any signal(sign) at the internal register? 

Then which part of internal register should I check out?

Or LOD function is just operated  as a display panel factory's initial mode?

If then, LOD detection function is maybe needed more circuit such as FPGA chip and memory chip etc..right?

  • 0
    TI__Genius 14295 points
    Hi, Kwak,

    I recommand you take a look at our application note SLVUAF0 for chapter 3.8 and 3.12.

    Let me know if you still have questions.

    Thanks.
    Regards,
    Kenneth
  • 0 in reply to Kenneth Du
    Prodigy 30 points

    Hi, Kenneth,

    Thank you for your reply.

    Your korean agent has also said to melike you.

    Actually I read 3.8 and 3.12 before, but I could not understand the concept of detecting LOD fully.

    I have 3 questions..

    1. LOD detection concept of TLC5957 is real time processing by comparator in every frame time? or TLC5957 store the position of led open area initially and remember that position permanently until power is off?

       What is the result of normal operation for LOD? output voltage is near GND level? NO output PWM current pulse waveforme is generated?

    2. Is the LOD concept  the same between 5957(static driver) and 5958(multiplexing driver? (By your application note, it will be the same i think)

    3. I guessed there is needed external circuit block(memory IC etc,) for detecting concept? No need?

    Thank you

  • 0 in reply to Jongwoon Kwak
    TI__Genius 14295 points
    Hi, Kwak,

    Please see my answer below:

    1. It is real time process.
    2. Yes. It's the same.
    3. No need, the IC will detect it automatically.

    Please help to click "Resolve" if the problem is solved.

    Thanks.
    Regards,
    Kenneth