The UCD9080 power-supply sequencer controls the enable sequence of up to eight independent voltage rails and provides four general-purpose digital outputs. The device operates from a 3.3-V supply, provides 3.2-mV resolution of voltage rails, and requires no external memory or clock. The UCD9080 monitors the voltage rails independently at more than a 20-kHz rate and has a high degree of rail sequence and rail error-response configurability. The sequencing of rails can be based on timed events or on timed events in conjunction with other rails achieving regulation or a voltage threshold. In addition, each rail is monitored for undervoltage and overvoltage glitches and thresholds. Each rail the UCD9080 monitors can be configured to shut down a user-defined set of other rails, and alarm conditions are monitored on a per-rail basis.
Figure 1 shows the UCD9080 power-supply sequencer in a typical application.