Data Sheet
FEATURES
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 V
IN
inputs
Low power consumption (15 μA)
Specified over –40°C to +125°C temperature range
6-lead SC70 package
Simple Sequencers
®
in 6-Lead SC70
ADM1085/ADM1086/ADM1087
FUNCTIONAL BLOCK DIAGRAMS
V
CC
ADM1085/ADM1086
V
IN
0.6V
CAPACITOR
ADJUSTABLE
DELAY
ENOUT
GND
CEXT
ENIN
V
CC
ADM1087
V
IN
CAPACITOR
ADJUSTABLE
DELAY
APPLICATIONS
Desktop/notebook computers, servers
Low power portable equipment
Routers
Base stations
Line cards
Graphics cards
0.6V
ENOUT
GND
CEXT
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
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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
Part No.
ADM1085
ADM1086
ADM1087
Enable Input
ENIN
ENIN
ENIN
Open-drain
Output Stage
ENOUT
ENOUT
Open-drain
Push-pull
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responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
04591-001
ADM1085/ADM1086/ADM1087
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Functional Block Diagrams ............................................................. 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 4
ESD Caution .................................................................................. 4
Pin Configuration and Function Descriptions ............................. 5
Typical Performance Characteristics ............................................. 6
Circuit Information .......................................................................... 9
Timing Characteristics and Truth Tables .................................. 9
Data Sheet
Capacitor-Adjustable Delay Circuit ............................................9
Open-Drain and Push-Pull Outputs ....................................... 10
Application Information ................................................................ 11
Sequencing Circuits ................................................................... 11
Dual LOFO Sequencing ............................................................ 13
Simultaneous Enabling .............................................................. 13
Power Good Signal Delays ........................................................ 13
Quad-Supply Power Good Indicator ....................................... 14
Sequencing with FET Switches ................................................. 14
Outline Dimensions ....................................................................... 15
Ordering Guide .......................................................................... 15
REVISION HISTORY
5/14—Rev. A to Rev. B
Removed ADM1088 ...................................................... Throughout
Changes to Capacitor-Adjustable Delay Circuit........................... 9
Removed Figure 26; Renumbered Sequentially.......................... 12
Changes to Ordering Guide .......................................................... 15
4/06—Rev. 0 to Rev. A
Added Lead-Free Models .................................................. Universal
Update Outline Dimensions ......................................................... 15
Changes to Ordering Guide .......................................................... 15
7/04—Revision 0: Initial Version
Rev. B | Page 2 of 16
Data Sheet
SPECIFICATIONS
V
CC
= full operating range, T
A
= −40°C to +125°C, unless otherwise noted.
Table 2.
Parameter
SUPPLY
V
CC
Operating Voltage Range
V
IN
Operating Voltage Range
Supply Current
V
IN
Rising Threshold, V
TH_RISING
V
IN
Falling Threshold, V
TH_FALLING
V
IN
Hysteresis
V
IN
to ENOUT/ENOUT Delay
V
IN
Rising
V
IN
Falling
V
IN
Leakage Current
CEXT Charge Current
Threshold Temperature Coefficient
ENIN/ENIN to ENOUT/ENOUT
Propagation Delay
ENIN/ENIN Voltage Low
ENIN/ENIN Voltage High
ENIN/ENIN Leakage Current
ENOUT/ENOUT Voltage Low
Min
2.25
0
0.56
0.545
10
0.6
0.585
15
35
2
20
170
250
30
0.5
Typ
Max
3.6
22
15
0.64
0.625
Unit
V
V
μA
V
V
mV
ADM1085/ADM1086/ADM1087
Test Conditions/Comments
V
CC
= 3.3 V
V
CC
= 3.3 V
125
375
μs
ms
μs
μA
nA
ppm/°C
μs
V
V
μA
V
CEXT floating, C = 20 pF
CEXT = 470 pF
V
IN
= V
TH_FALLING
to (V
TH_FALLING
− 100 mV)
V
IN
= 22 V
V
IN
> V
TH_RISING
0.3 V
CC
− 0.2
0.3 V
CC
+ 0.2
170
0.4
ENOUT/ENOUT Voltage High
(ADM1086)
ENOUT/ENOUT Open-Drain Output
Leakage Current (ADM1085/ADM1087)
0.8 V
CC
V
0.4
μA
ENIN/ENIN = 22 V
V
IN
< V
TH_FALLING
(ENOUT),
V
IN
> V
TH_RISING
(ENOUT),
I
SINK
= 1.2 mA
V
IN
> V
TH_RISING
(ENOUT),
V
IN
< V
TH_FALLING
(ENOUT),
I
SOURCE
= 500 μA
ENOUT/ENOUT = 22 V
Rev. B | Page 3 of 16
ADM1085/ADM1086/ADM1087
ABSOLUTE MAXIMUM RATINGS
T
A
= 25°C, unless otherwise noted.
Table 3.
Parameter
V
CC
V
IN
CEXT
ENIN, ENIN
ENOUT, ENOUT (ADM1085,
ADM1087)
ENOUT, ENOUT (ADM1086)
Operating Temperature Range
Storage Temperature Range
θ
JA
Thermal Impedance, SC70
Lead Temperature
Soldering (10 sec)
Vapor Phase (60 sec)
Infrared (15 sec)
Rating
−0.3
V to +6 V
−0.3
V to +25 V
−0.3
V to +6 V
−0.3
V to +25 V
−0.3
V to +25 V
−0.3
V to +6 V
−40°C
to +125°C
−65°C
to +150°C
146°C/W
300°C
215°C
220°C
Data Sheet
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
ESD CAUTION
Rev. B | Page 4 of 16
Data Sheet
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
ENIN/ENIN
1
GND
2
V
IN 3
ADM1085/ADM1086/ADM1087
ADM1085/
ADM1086/
ADM1087
6
5
V
CC
CEXT
04591-002
4
ENOUT/ENOUT
TOP VIEW
(Not to Scale)
Figure 2. Pin Configuration
Table 4. Pin Function Descriptions
Pin No.
1
2
3
Mnemonic
ENIN, ENIN
GND
V
IN
Description
Enable Input. Controls the status of the enable output. Active high for
ADM1085/ADM1086.
Active low for
ADM1087.
Ground.
Input for the Monitored Voltage Signal. Can be biased via a voltage divider resistor network to customize the
effective input threshold. Can precisely monitor an analog power supply output signal and detect when it has
powered up. The voltage applied at this pin is compared with a 0.6 V on-chip reference. With this reference,
digital signals with various logic level thresholds can also be detected.
Enable Output. Asserted when the voltage at V
IN
is above V
TH_RISING
and the time delay has elapsed, provided
that the enable input is asserted. Active high for the
ADM1085/ADM1086.
Active low for the
ADM1087.
External Capacitor Pin. The capacitance on this pin determines the time delay on the enable output. The delay
is seen only when the voltage at V
IN
rises past V
TH_RISING
, and not when it falls below V
TH_FALLING
.
Power Supply.
4
5
6
ENOUT, ENOUT
CEXT
V
CC
Rev. B | Page 5 of 16
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