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. 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.
During a power-up sequence, the state machine enables each power supply in turn. The supply output voltage is monitored to determine whether it rises above the UV threshold level within a user defined duration called the blanking time. If a supply rises above the UV threshold, the next enable output in the sequence is turned on. In addition to the blanking time, the user can also define a sequence time delay before each enable output is turned on.
The ADM1186-1 provides an open-drain pin, SEQ_DONE, that is asserted high to provide an indication that a power-up sequence is complete. The SEQ_DONE pin allows multiple cascaded ADM1186-1 devices to perform controlled power-up and power-down sequences.
During a power-down sequence, the enable outputs turn off in reverse order. The same sequence time delays used during the power-up sequence are also used during the power-down sequence as each enable output is turned off; no blanking time is used during a power-down sequence. At the end of a powerdown sequence, the SEQ_DONE pin is brought low.
During sequencing and when powered up, the state machine continuously monitors the part for any fault conditions. Faults include a UV condition on any of the inputs or an unexpected control input. Any fault causes the state machine to enter a fault handler, which immediately turns off all enable outputs and then ensures that the device is ready to start a new power-up sequence.
The ADM1186-1 has a bidirectional pin, FAULT, that facilitates fault handling when using multiple devices. If an ADM1186-1 experiences a fault condition, the FAULT pin is driven low, causing other connected ADM1186-1 devices to enter their own fault handling states.
The ADM1186-1 is available in a 20-lead QSOP package, and the ADM1186-2 is available in a 16-lead QSOP package.
ADI ADM1186-2ARQZ