The ADM1186-1 and ADM1186-2 are integrated， four-channel voltage monitoring and sequencing devices. A 2.7 V to 5.5 V power supply is required on the VCC pin for power. Four precision comparators， VIN1 to VIN4， monitor four voltage rails. All four comparators share a 0.6 V reference and have a worst-case accuracy of 0.8%. Resistor networks that are external to the VIN1， VIN2， VIN3， and VIN4 pins set the undervoltage （UV） trip points for the monitored supply rails. The ADM1186-1 and ADM1186-2 have four open-drain enable outputs， OUT1 to OUT4， that are used to enable power supplies. An open-drain power-good output， PWRGD， indicates whether the four VINx inputs are above their UV thresholds. A state machine monitors the state of the UP and DOWN pins on the ADM1186-1 or the UP/DOWN pin on the ADM1186-2 to control the supply sequencing direction （see Figure 2）。 In the WAIT START state， a rising edge transition on the UP or UP/DOWN pin triggers a power-up sequence. A falling edge transition on the DOWN or UP/DOWN pin in the POWER-UP DONE state triggers a power-down sequence