App note from Maxim Integrated about current DACs and their uses. Link here
The worldwide use of the electronic devices creates high demands for DACs to connect digital systems to the analog world such as the fiber optical communication networks, to bias photo diodes or to digitally control analog devices such as power supplies to precisely deliver stable, high-resolution currents from the very low microamps to hundreds of milliamps. The output stage of a DAC can be designed to provide a voltage or current output. This application note discusses the current output type and its intended applications.