Suggestions for DC/DC converters with digital control
Two things to think about.

First, even "analog" power supply control chips can be "digitally controlled", whatever that really means.  A little external tweaking of the feedback and the output voltage can be varied.  Many have shutdown inputs, but of course that can be accomplished other ways too.

Second, for fancy switching power supply control you can use a microcontroller directly, and obviously have all the digital control you care to program in.  There are whole families of microcontrollers specifically intended for this sort of application.  They have fast A/Ds, decent computer power, and fancy PWM modules that not only have high resolution but additional features like external shutdown modes, complementary outputs, etc.  Check out the dsPIC 33F line from Microchip.  All the high end switching power supply applications we've dealt with in recent years have had a microcontroller doing the closed loop control.  Dedicated chips are more for simple power supplies, like running the microcontroller.