Power sequencing from Analog Devices using their ADP5134 sequencer IC. App note here (PDF)
Power supply sequencing is required for microcontrollers, field programmable gate arrays (FPGAs), digital signal processors(DSPs), analog-to-digital converters (ADCs), and other devices that operate from multiple voltage rails. These applications typically require that the core and analog blocks be powered up before the digital input/output (I/O)rails, although some designs may require other sequences. Proper power-up and power-down sequencing can prevent both immediate damage from latch-up and long-term damage from electrostatic discharge (ESD). In addition, sequencing the supplies staggers the inrush current during power-up, an especially helpful technique in applications operating from current-limited supplies.