Power Supply Sequencing

摘要

The number of power supply rails within a system contin-ues to expand. To avoid internal latch-up and potential damage to the processor or FPGA, the I/O and core voltage ramp-up sequence is strictly defined. The relationship between I/O and core voltages varies with the application. In a majority of applications, ramping up the supplies simultaneously (tracking) meets the requirement. Assuring the supplies turn on and off in the proper sequence can be a significant challenge depending on the arrangement of these supplies. If all supplies use the same input supply, then it may be simple. It becomes more complex if the output of one supply is the input to the next. Mixing power modules with switching and linear regulators further complicates the situation. Linear Technology offers simple solutions to tame the unruly supplies by turning them on and off in the proper manner. The choice between the three new products depends on the type of power supply used and whether voltage tracking or sequencing is required.