资 源 简 介
The ADM1085/ADM1086/ADM1087 are simple sequencing circuits that provide a TIme delay between the enabling of voltage regulators and/or dc-dc converters at power-up in mulTIple supply systems. When the output voltage of the first power module reaches a preset threshold， a TIme delay is iniTIated before an enable signal allows subsequent regulators to power up. Any number of these devices can be cascaded with regulators to allow sequencing of multiple power supplies.
Threshold levels can be set with a pair of external resistors in a voltage divider configuration. With appropriate resistor values， the threshold can be adjusted to monitor voltages as low as 0.6 V.
The ADM1086 has a push-pull output stage， with active high （ENOUT）。 The ADM1085 has an active-high （ENOUT） logic output; the ADM1087 has an active-low （ENOUT） output. Both the ADM1085 and ADM1087 have open-drain output stages that can be pulled up to voltage levels as high as 22 V through an external resistor. This level-shifting property ensures compatibility with enable input logic levels of different regulators and converters.
All four models have a dedicated enable input pin that allows the output signal to the regulator to be controlled externally. This is an active high input （ENIN） for the ADM1085 andADM1086， and an active low input （ENIN） for the ADM1087.
The Simple Sequencers are specified over the extended −40°C to +125°C temperature range. With low current consumption of 15 μA （typical） and 6-lead SC70 packaging， the parts are suitable for low-power portable applications.
