TLC5945 TLC5943 CASCADING up to 256 chips

Hello Michel,

The problem with cascading the parts is that the data is shifted through all parts and the SCLK signal is directly connected to all parts at the same time. This generates some issues if you cascade a lot of these parts in series. Especially the SCLK signal might get rounded edges and slower slopes due to the board parasitics.

You must be careful to ensure the TLC594x setup and hold requirements are met.  If your signal drive strength is too low, the signal edges will be rounded due to the board capacitance on the data and clock lines.  There is no requirement to buffer the clock or any other signals.  However, depending on your specific drive strengths, board capacitances, clock speeds, timing between signals, you may need to buffer your signals to meet the TLC594x timing requirements.  If you are at the limits of the setup and hold requirements and have rounded edges on your clock and data signals, you might be able to shift the timing between your signals to resolve the problem.  It may require a buffer.

So the sentence on page 18 gives the experience on the above problem. If you are cascading such a lot TLC594x devices, I would recommend to add clock buffers to make sure that the timings are fulfilled. The number might be a little different on TLC5943 compared to TLC5945 because of different delays in the system, but you will face a similar issue.

Best regards,
Brigitte

THANKS , Brigitte !
This is EXACTLY the info we are looking for !
So we need to put some  CLOCK FAN OUT Buffer in the design.
I Cannot find easily a Chip on Texas web , with  a mini Frequency of 5Mhz ( the Mini clock frequency the customer want to use)
And the possibility to adjust individually the Phase of each OutPut
Do you have any idea ?
Michel