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TLC5924: Problem programming TLC5924 with a micro - HELP

Paghi
Prodigy 10 points
Part Number: TLC5924

Hi there, I have recently buyed some TLC5924 LED IC driver. I'm trying to configure the LED IC using an ARM7 microcontroller (ADuC7020).

I'm sending the 112 bit DOT data with MODE HI, followed by an XLAT pulse (tHI=200ns), then the 16 bit for ON/OFF selection with MODE LO, again followed by an XLAT pulse. A that point I toggle the BLANK signal, really slowsly, with a period os aome ms, but nothing happen, I can't see my LED toggling.


Some detail: Vcc,Vup and VLed are at the same voltage  (3.3V). The SCLK frequency is 3.4MHz. XLAT is a pulse of about 200ns following the serial data transmission. I have seen all the signal sent with my OSC, but I really don't understand what I'm missing.

Attached are the schematics, and the signal captured with the OSC. In this example I'm just programming the current level of the first led (OUT0) sending  112bit, where only the last seven bit are not zero (DC0=35  so the last seven bit are 0100011). and setting only the OUT0 (000000000000000001).

Maybe I haven't understud the Timing Chart or it is the IC that doesn't work? Can anyone help me please?

TLC5924.pdf

  • 0
    TI__Expert 5675 points
    Hi Paghi,

    When MODE = H (DC data mode), XLAT is a level-triggered latch signal of dot correction registers.
    The serial data in DC input shift registers is written into dot correction registers when XLAT = H.
    The data in dot correction registers is held constant when XLAT = L.

    So you need to keep XLAT high when write DC data.

    Best regards,
    Jason