ADM1085/ADM1086/ADM1087: Simple Sequencers® in 6-Lead SC700 pages

Simple Sequencers® in 6-Lead SC70
ADM1085/ADM1086/ADM1087

Data Sheet
FEATURES

FUNCTIONAL BLOCK DIAGRAMS
VCC

ADM1085/ADM1086
VIN

CAPACITOR
ADJUSTABLE
DELAY

0.6V

GND

CEXT

ENOUT

ENIN

VCC

ADM1087
VIN

CAPACITOR
ADJUSTABLE
DELAY

0.6V

APPLICATIONS
Desktop/notebook computers, servers
Low power portable equipment
Routers
Base stations
Line cards
Graphics cards

GND

CEXT

ENOUT

04591-001

Provide programmable time delays between enable
signals
Can be cascaded with power modules for multiple
supply sequencing
Power supply monitoring from 0.6 V
Output stages
High voltage (up to 22 V) open-drain output
(ADM1085/ADM1087)
Push-pull output (ADM1086)
Capacitor-adjustable time delays
High voltage (up to 22 V) enable and VIN inputs
Low power consumption (15 μA)
Specified over –40°C to +125°C temperature range
6-lead SC70 package

ENIN

Figure 1.

GENERAL DESCRIPTION
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.
Rev. B

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 and
ADM1086, 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.
Table 1. Selection Table
Output Stage
ENOUT
ENOUT

Part No.

Enable Input

ADM1085

ENIN

Open-drain

ADM1086

ENIN

Push-pull

ADM1087

ENIN

Open-drain

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