ANALOG DEVICES ADM1087 Service Manual

V

V

V

www.BDTIC.com/ADI

Simple Sequencers® in 6-Lead SC70

FEATURES

Provide programmable time delays between enable

signals

Can be cascaded with power modules for multiple

sup

ply 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
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

inputs

IN

ADM1085/ADM1086/ADM1087/ADM1088

FUNCTIONAL BLOCK DIAGRAMS

CC

ADM1085/ADM1086

GND

GND

CAPACITOR

ADJUSTABLE

DELAY

V

CC

CAPACITOR

ADJUSTABLE

DELAY

Figure 1.

ENOUT

ENINCEXT

ENOUT

ENINCEXT

IN

0.6V

ADM1087/ADM1088

IN

0.6V

04591-001

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
v

oltage divider configuration. With 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,

ith active high (ENOUT) and active low (

w

ENOUT

) logic

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
property ensures compatibility with enable input logic levels of
different regulators and converters.

Rev. A

Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her
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.

All four models have a dedicated enable input pin that allows

he output signal to the regulator to be controlled externally.

t
This is an active high input (ENIN) for the ADM1085 and
ADM1086, and an active low input (

) for the ADM1087

ENIN

and ADM1088.

The Simple Sequencers are specified over the extended

−40°C t

o +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
Part No. Enable Input

ADM1085 ENIN

ADM1086 ENIN

ADM1087

ADM1088

ENIN

ENIN

ENOUT

Open-drain

Push-pull

ENOUT

Open-drain

Push-pull

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] ©2006 Analog Devices, Inc. All rights reserved.

ADM1085/ADM1086/ADM1087/ADM1088

www.BDTIC.com/ADI

TABLE OF CONTENTS

Features .............................................................................................. 1

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

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

REVISION HISTORY

4/06—Rev. 0 to Rev. A

Added Lead-Free Models ..................................................Universal

Update Outline Dimensions ......................................................... 15

Changes to Ordering Guide.......................................................... 15

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

7/04—Revision 0: Initial Version

Rev. A | Page 2 of 16

ADM1085/ADM1086/ADM1087/ADM1088

www.BDTIC.com/ADI

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 = V
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

TH_FALLING

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

IN

> V

TH_RISING

ENIN/ENIN = 22 V
VIN < V

TH_FALLING

VIN > V
I

= 1.2 mA

SINK

> V

V

IN

V

< V

IN

I

SOURCE

(ENOUT),

TH_RISING

(ENOUT),

TH_RISING

TH_FALLING

= 500 μA

ENOUT/ENOUT = 22 V

to (V

TH_FALLING

(ENOUT),

(ENOUT),

– 100 mV)

Rev. A | Page 3 of 16

ADM1085/ADM1086/ADM1087/ADM1088

www.BDTIC.com/ADI

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 sec) 300°C
Vapor Phase (60 sec) 215°C
Infrared (15 sec) 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
ma

y 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

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. A | Page 4 of 16

ADM1085/ADM1086/ADM1087/ADM1088

www.BDTIC.com/ADI

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

ADM1085/

Table 4. Pin Function Descriptions

Pin No. Mnemonic Description

1

ENIN, ENIN

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

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

ective input threshold. Can precisely monitor an analog power supply output signal and detect when it has

eff

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 dela

is seen only when the voltage at V
6 VCC Power Supply.

ENIN/ENIN

GND

V

1

ADM1086/
ADM1087/

2

ADM1088

3

TOP VIEW

IN

(Not to Scale)

Figure 2. Pin Configuration

rises past V

IN

6

5

4

V

CC

CEXT

ENOUT/ENOUT

04591-002

and the time delay has elapsed, provided

TH_RISING

, and not when it falls below V

TH_RISING

y on the enable output. The delay

.

TH_FALLING

Rev. A | Page 5 of 16