Switching a ULN darlington array from TLC5940 driver?
You can use pull-ups on the output of the TLC5940 and this can form a voltage output device depending on what current is programmed for the sink. Say you programmed 10mA and the supply was 5V. If you used a 500 ohm pull-up resistor, the output would be close to 0V i.e. not driving the ULN2004A. If you programmed the current to be 1mA, the output would be about 4.5V and plenty to turn on the ULN2004A.

You've just got to remember the output is inverted.

If you found an PNP darlington array (common point to positive rail) then it wouldn't be inverted.