Constant current "driver"
Do you mean you want your Vout to be strictly 0v?

The chip you found have a constant current sink. If you have a current-driven device like LED, it's ok to let your Vout have some voltage like 0.2v or more. 
This does not affect your device. And for LED case the the current control the brightness and the internal resistance control the voltage drop across the LED. If u give 12v Vdd and voltage drop for LED needed is 3v the rest 9v must be eaten by the driver. This will make your IC very hot.

U can try TLC5940, it have 16 channel constant current sink and 120ma per channel.