ANALOG DEVICES ADM1085, ADM1086, ADM1088 Service Manual

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ADM1085/ADM1086/ADM1087/ADM1088

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/ADM1088)
Capacitor-adjustable time delays
High voltage (up to 22 V) Enable and V

inputs

IN

Low power consumption (15 µA)
Specified over –40°C to +125°C temperature range
6-lead SC70 package

APPLICATIONS

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

GENERAL DESCRIPTION

The ADM1085/ADM1086/ADM1087/ADM1088 are simple
sequencing circuits that provide a time delay between the
enabling of voltage regulators and/or dc-dc converters at power­up 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. By choosing appropriate resistor
values, the threshold can be adjusted to monitor voltages as low
as 0.6 V.

The ADM1086 and ADM1088 have push-pull output stages,
with active-high (ENOUT) and active-low (

ENOUT
outputs, respectively. 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

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable.
However, no 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.

) logic

Simple Sequencers™ in 6-Lead SC70

FUNCTIONAL BLOCK DIAGRAMS

ADM1085/ADM1086

IN

0.6V

GND

ADM1087/ADM1088

IN

0.6V

GND

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 and
ADM1086, and an active-low input (
and ADM1088.

The simple sequencers are specified over the extended −40°C to
+125°C temperature range. With low current consumption of 15
µA (typ) and 6-lead SC70 packaging, the parts are suitable for
low-power portable applications.

Table 1. Selection Table

Part No. Enable Input

ADM1085 ENIN Open-Drain
ADM1086 ENIN Push-Pull
ADM1087

ADM1088

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone]
Fax: [phone] © 2004 Analog Devices, Inc. All rights reserved.

ENIN
ENIN

www.analog.com

CC

CAPACITOR

ADJUSTABLE

DELAY

ENINCEXT

V

CC

CAPACITOR

ADJUSTABLE

DELAY

ENINCEXT

Figure 1.

ENIN

) for the ADM1087

Output Stage

ENOUT

ENOUT

Open-Drain
Push-Pull

ENOUT

ENOUT

04591-PrG-001

ADM1085/ADM1086/ADM1087/ADM1088

TABLE OF CONTENTS

Specifications..................................................................................... 3

Application Information................................................................ 11

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

Capacitor-Adjustable Delay Circuit........................................... 9

Open-Drain and Push-Pull Outputs ....................................... 10

REVISION HISTORY

7/04—Revision 0: Initial Version

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

Rev. 0 | Page 2 of 16

ADM1085/ADM1086/ADM1087/ADM1088

SPECIFICATIONS

VCC = full operating range, TA = −40°C to +125°C, unless otherwise noted.

Table 2.

Parameter Min Typ Max Unit Test Conditions/Comments

SUPPLY

VCC Operating Voltage Range 2.25 3.6 V
VIN Operating Voltage Range 0 22 V

Supply Current 10 15 µA
VIN Rising Threshold, V
VIN Falling Threshold, V

TH_RISING

TH_FALLING

VIN Hysteresis 15 mV
VIN to ENOUT/ENOUT Delay

VIN Rising 35 µs CEXT floating, C = 20 pF

2 ms CEXT = 470 pF

VIN Falling 20 µs

VIN Leakage Current 170 µA VIN = 22 V
CEXT Charge Current 125 250 375 nA
Threshold Temperature Coefficient 30 ppm/°C
ENIN/ENIN TO ENOUT/ENOUT Propagation

Delay
ENIN/ENIN Voltage Low

ENIN/ENIN Voltage High
ENIN/ENIN Leakage Current
ENOUT/ENOUT Voltage Low

ENOUT

ENOUT/

Voltage High

(ADM1086/ADM1088)

ENOUT

ENOUT/

Open-Drain Output Leakage

Current (ADM1085/ADM1087)

0.56 0.6 0.64 V VCC = 3.3 V

0.545 0.585 0.625 V VCC = 3.3 V

= V

V

IN

TH_FALLING

100 mV)

0.5 µs V

0.3 V

0.3 V

+ 0.2 V

CC

− 0.2 V

CC

170 µA

0.4 V

0.8 V

CC

V

0.4 µA

> V

IN

ENIN

ENIN/
VIN < V

> V

V

IN

I

= 1.2 mA

SINK

> V

V

IN

< V

V

IN

I

= 500 µA

SOURCE

ENOUT/

TH_RISING

TH_FALLING

TH_RISING

TH_RISING

TH_FALLING

ENOUT

to (V

= 22 V

(ENOUT),
ENOUT

(

(ENOUT),

ENOUT

(

= 22 V

TH_FALLING

),

),

–

Rev. 0 | Page 3 of 16

ADM1085/ADM1086/ADM1087/ADM1088

ABSOLUTE MAXIMUM RATINGS

TA = 25°C, unless otherwise noted.

Table 3.

Parameter Rating

V

CC

V

IN

CEXT
ENIN, ENIN

ENOUT, ENOUT (ADM1085, ADM1087)

ENOUT, ENOUT (ADM1086, ADM1088)

Operating Temperature Range

Storage Temperature Range
θJA Thermal Impedance, SC70 146°C/W
Lead Temperature

Soldering (10 s) 300°C
Vapor Phase (60 s) 215°C
Infrared (15 s) 220°C

−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

Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only and 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

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on
the human body and test equipment and can discharge without detection. Although this product features
proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy
electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance
degradation or loss of functionality.

Rev. 0 | Page 4 of 16

ADM1085/ADM1086/ADM1087/ADM1088

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

Table 4. Pin Function Descriptions

Pin No. Mnemonic Description

1

ENIN Enable Input. Controls the status of the enable output. Active high for ADM1085/ADM1086. Active low for

ENIN,

ADM1087/ADM1088.
2 GND Ground.
3 VIN

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.
4

ENOUT,

ENOUT Enable Output. Asserted when the voltage at VIN is above V

that the enable input is asserted. Active high for the ADM1085/ADM1086. Active low for the

ADM1087/ADM1088.
5 CEXT

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
6 VCC Power Supply.

ENIN/ENIN

GND

V

ADM1085/

1

2

3

IN

ADM1086/
ADM1087/

ADM1088

TOP VIEW

(Not to Scale)

6

5

4

Figure 2. Pin Configuration

rises past V

IN

V

CC

CEXT

ENOUT/ENOUT

04591-PrG-002

and the time delay has elapsed, provided

TH_RISING

, and not when it falls below V

TH_RISING

TH_FALLING

.

Rev. 0 | Page 5 of 16