The circuit is very straightforward. The LTC2640 provides the reference voltage to the output stage. This voltage can be adjusted via SPI, form 0 to 4.095V. The output stage is essentially comprised of a NPN transistor in the emitter follower configuration, which has its base polarized by an OPA705 op-amp. The short circuit protection is made by an additional NPN transistor that "starves" the base of the power NPN transistor when the output current stays above a certain threshold.