Tool/software:
Hello,
I have 4x TLC59291 cascaded, with common blank/latch/clock and sout connected to the next device in sequence. On the final device I have no termination (sout left unconnected). My traces are not impedance controlled but are fairly short (<100mm) and clocked fairly slowly (~100kHz). I can shift display control data in across the 4 displays and this is displayed fine, however there appears to be strange behaviour when attempting to latch control data. I am sending 4x16b words in a transmission with the 7 LSB of each word set to control brightness. I have modified the clock signal to remain high on the final pulse of the transmission (i.e 64th) until latch is toggled high, but only the 2nd and 4th displays appear to respond to this brightness control. When the 7-bit brightness control value is adjusted the brightness also seems to change somewhat randomly. I have confirmed with a logic analyser that the value being transmitted is correct and the data/clock/latch lines appear to match the timing diagram for sending control data.
Additionally, I have noted that on displays 3 and 4, the LEDs connected to OUT9 appear to glow dimly whenever a voltage is applied to the TLC59291. I have determined that there is a resistance of approximately 0.9kohm and 1.1kohm from this pin to ground but I cannot determine the source of this. There is nothing else connected to this trace other than the TLC59291.
