Arduino + TLC5940 + CAT4101
You connect the base of any small-signal PNP transistor (for example: BC327, BC807, BC556/557/558, 2N3906) to the output of the TLC via a series resistor (500-10k ohms). The emitter of the transistor goes to Vdd, the collector goes to the input of the CAT. Another parallel resistor (1k-50k ohms) should be connected between the input of the CAT and GND.

You should configure the TLC to generate only a small (&lt;1mA) current, by selecting the maximum reference current resistor value supported (see page 14 of the TLC data sheet), and programming the dot correction to lower the current.







simulate this circuit &ndash; Schematic created using CircuitLab