AD ADM1085 Simple sequencers in 6-lead sc70 Datasheet

Simple Sequencers™ in 6-Lead SC70
ADM1085/ADM1086/ADM1087/ADM1088
FUNCTIONAL BLOCK DIAGRAMS
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 VIN inputs
Low power consumption (15 µA)
Specified over –40°C to +125°C temperature range
6-lead SC70 package
VCC
ADM1085/ADM1086
VIN
CAPACITOR
ADJUSTABLE
DELAY
0.6V
GND
CEXT
ENOUT
ENIN
VCC
ADM1087/ADM1088
VIN
CAPACITOR
ADJUSTABLE
DELAY
0.6V
ENOUT
Desktop/notebook computers, servers
Low power portable equipment
Routers
Base stations
Line cards
Graphics cards
GND
CEXT
04591-PrG-001
APPLICATIONS
ENIN
Figure 1.
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) 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.
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
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
Output Stage
Part No.
ADM1085
ADM1086
ADM1087
ADM1088
Enable Input
ENIN
ENIN
ENIN
ENIN
ENOUT
ENOUT
Open-Drain
Push-Pull
Open-Drain
Push-Pull
Rev. 0
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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
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registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.326.8703
© 2004 Analog Devices, Inc. All rights reserved.
ADM1085/ADM1086/ADM1087/ADM1088
TABLE OF CONTENTS
Specifications..................................................................................... 3
Application Information................................................................ 11
Absolute Maximum Ratings............................................................ 4
Sequencing Circuits ................................................................... 11
ESD Caution.................................................................................. 4
Dual LOFO Sequencing ............................................................ 13
Pin Configuration and Function Descriptions............................. 5
Simultaneous Enabling.............................................................. 13
Typical Performance Characteristics ............................................. 6
Power Good Signal Delays........................................................ 13
Circuit Information .......................................................................... 9
Quad-Supply Power Good Indicator....................................... 14
Timing Characteristics and Truth Tables.................................. 9
Sequencing with FET Switches................................................. 14
Capacitor-Adjustable Delay Circuit........................................... 9
Outline Dimensions ....................................................................... 15
Open-Drain and Push-Pull Outputs ....................................... 10
Ordering Guide .......................................................................... 15
REVISION HISTORY
7/04—Revision 0: Initial Version
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
SUPPLY
VCC Operating Voltage Range
VIN Operating Voltage Range
Supply Current
VIN Rising Threshold, VTH_RISING
VIN Falling Threshold, VTH_FALLING
VIN Hysteresis
VIN to ENOUT/ENOUT Delay
VIN Rising
Min
2.25
0
0.56
0.545
ENOUT/ENOUT Voltage High
(ADM1086/ADM1088)
ENOUT/ENOUT Open-Drain Output Leakage
Current (ADM1085/ADM1087)
10
0.6
0.585
15
Max
Unit
3.6
22
15
0.64
0.625
V
V
µA
V
V
mV
35
2
20
VIN Falling
VIN 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
Typ
125
170
250
30
0.5
µs
ms
µs
375
0.3 VCC − 0.2
0.3 VCC + 0.2
170
0.4
µA
nA
ppm/°C
µs
V
V
µA
V
V
0.8 VCC
0.4
Rev. 0 | Page 3 of 16
µA
Test Conditions/Comments
VCC = 3.3 V
VCC = 3.3 V
CEXT floating, C = 20 pF
CEXT = 470 pF
VIN = VTH_FALLING to (VTH_FALLING –
100 mV)
VIN = 22 V
VIN > VTH_RISING
ENIN/ENIN = 22 V
VIN < VTH_FALLING (ENOUT),
VIN > VTH_RISING (ENOUT),
ISINK = 1.2 mA
VIN > VTH_RISING (ENOUT),
VIN < VTH_FALLING (ENOUT),
ISOURCE = 500 µA
ENOUT/ENOUT = 22 V
ADM1085/ADM1086/ADM1087/ADM1088
ABSOLUTE MAXIMUM RATINGS
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.
TA = 25°C, unless otherwise noted.
Table 3.
Parameter
VCC
VIN
CEXT
ENIN, ENIN
ENOUT, ENOUT (ADM1085, ADM1087)
ENOUT, ENOUT (ADM1086, ADM1088)
Rating
−0.3 V to +6 V
−0.3 V to +25 V
Operating Temperature Range
Storage Temperature Range
θJA Thermal Impedance, SC70
Lead Temperature
Soldering (10 s)
Vapor Phase (60 s)
Infrared (15 s)
−40°C to +125°C
−65°C to +150°C
146°C/W
−0.3 V to +6 V
−0.3 V to +25 V
−0.3 V to +25 V
−0.3 V to +6 V
300°C
215°C
220°C
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
ENIN/ENIN 1
GND 2
VIN 3
ADM1085/
ADM1086/
ADM1087/
ADM1088
6
VCC
5
CEXT
4 ENOUT/ENOUT
TOP VIEW
(Not to Scale)
04591-PrG-002
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
Figure 2. Pin Configuration
Table 4. Pin Function Descriptions
Pin No.
1
Mnemonic
ENIN, ENIN
2
3
GND
VIN
4
ENOUT, ENOUT
5
CEXT
6
VCC
Description
Enable Input. Controls the status of the enable output. Active high for ADM1085/ADM1086. Active low for
ADM1087/ADM1088.
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 VIN is above VTH_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/ADM1088.
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 VIN rises past VTH_RISING, and not when it falls below VTH_FALLING.
Power Supply.
Rev. 0 | Page 5 of 16
ADM1085/ADM1086/ADM1087/ADM1088
TYPICAL PERFORMANCE CHARACTERISTICS
200
680
180
660
160
640
620
600
580
560
VTRIP FALLING
04591-PrG-003
540
520
500
–40
–25
–10
5
20
35
50
65
TEMPERATURE (°C)
80
95
110
140
TA = +25°C
120
100
80
TA = –40°C
60
40
20
0
125
0
Figure 3. VIN Threshold vs. Temperature
4
6
8
10
12
VIN (V)
16
18
20
22
200
190
11.5
TA = +25°C
VIN LEAKAGE CURRENT (µA)
11.0
10.5
10.0
TA = +125°C
TA = –40°C
9.5
04591-PrG-004
9.0
8.5
8.0
2.10
2.40
2.70
3.00
3.30
TA = +125°C
180
170
160
TA = +25°C
150
140
TA = –40°C
130
120
110
100
2.10
3.60
VCC (V)
2.40
2.70
3.00
3.30
3.60
VCC (V)
Figure 4. Supply Current vs. Supply Voltage
Figure 7. VIN Leakage Current vs. VCC Voltage
20
10000
TA = +125°C
18
16
1000
12
10
8
6
4
2
0
0
2
4
6
8
10
12
VIN (V)
14
16
18
20
TA = +25°C
100
TA = –40°C
10
1
0.1
0.01
22
Figure 5. Supply Current vs. VIN Voltage
04591-PrG-008
OUTPUT VOLTAGE (mV)
14
04591-PrG-005
SUPPLY CURRENT (µA)
14
Figure 6. VIN Leakage Current vs. VIN Voltage
12.0
ICC (µA)
2
04591-PrG-007
VTRIP (mV)
VTRIP RISING
TA = +125°C
04591-PrG-006
VIN LEAKAGE CURRENT (µA)
700
0.1
1
10
OUTPUT SINK CURRENT (mA)
20
Figure 8. Output Voltage vs. Output Sink Current
Rev. 0 | Page 6 of 16
100
ADM1085/ADM1086/ADM1087/ADM1088
200
120
180
ENIN/ENIN LEAKAGE (µA)
80
60
40
0
2.10
2.40
2.70
3.00
SUPPLY VOLTAGE (V)
3.30
120
100
TA = –40°C
80
60
20
0
3.60
0
Figure 9. Output Low Voltage vs. Supply Voltage
100
200
90
180
80
160
70
140
4
6
8
10
12
14
ENIN/ENIN (V)
16
18
20
22
ENIN LEAKAGE (µA)
TA = +125°C
1mV/µs
50
40
10mV/µs
30
20
10
–25
–10
5
20
35
50
65
TEMPERATURE (°C)
80
95
110
TA = +25°C
TA = –40°C
120
100
80
60
40
04591-PrG-013
60
0
–40
2
Figure 12. ENIN/ENIN Leakage Current vs. ENIN/ENIN Voltage
04591-PrG-010
PROPAGATION DELAY (µs)
140
04591-PrG-012
20
TA = +25°C
40
04591-PrG-009
OUTPUT LOW VOLTAGE (mV)
TA = +125°C
160
100
20
0
2.10
125
2.40
2.70
3.00
3.30
3.60
VCC (V)
Figure 10. VCC Falling Propagation Delay vs. Temperature
Figure 13. ENIN/ENIN Leakage Current vs. VCC Voltage
10000
500
450
1000
400
CEXT (nF)
300
250
200
100
10
150
50
0
2.10
1
2.40
2.70
3.00
SUPPLY VOLTAGE (V)
3.30
0.1
0.562 2.390
3.60
Figure 11. Output Fall Time vs. Supply Voltage
04591-PrG-014
100
04591-PrG-011
FALL TIME (ns)
350
5.02
22.9 53.2
241
520
TIMEOUT DELAY (ms)
2350
4480 26200
Figure 14. CEXT Capacitance vs. Timeout Delay
Rev. 0 | Page 7 of 16
300
100
280
90
260
80
240
220
200
180
160
04591-PrG-015
140
120
100
–40
–25
–10
5
20
35
50
65
TEMPERATURE (°C)
80
95
110
90
70
60
50
40
30
04591-PrG-016
PROPAGATION DELAY (µs)
80
0
–40
–25
–10
5
20
35
50
65
TEMPERATURE (°C)
80
95
110
50
40
30
20
10
0
10
100
COMPARATOR OVERDRIVE (mV)
1000
Figure 17. Maximum VIN Transient Duration vs. Comparator Overdrive
100
10
60
1
125
Figure 15. CEXT Charge Current vs. Temperature
20
70
04591-PrG-017
TRANSIENT DURATION (µs)
CHARGE CURRENT (nA)
ADM1085/ADM1086/ADM1087/ADM1088
125
Figure 16. VIN to ENOUT/ENOUT Propagation Delay
(CEXT Floating) vs. Temperature
Rev. 0 | Page 8 of 16
ADM1085/ADM1086/ADM1087/ADM1088
CIRCUIT INFORMATION
TIMING CHARACTERISTICS AND TRUTH TABLES
When VIN reaches the upper threshold voltage (VTH_RISING), an
internal circuit generates a delay (tEN) before the enable output
is asserted. If VIN drops below the lower threshold voltage
(VTH_FALLING), the enable output is deasserted immediately.
The enable outputs of the ADM1085/ADM1086/ADM1087/
ADM1088 are related to the VIN and enable inputs by a simple
AND function. The enable output is asserted only if the enable
input is asserted and the voltage at VIN is above VTH_RISING, with
the time delay elapsed. Table 5 and Table 6 show the enable
output logic states for different VIN/enable input combinations
when the capacitor delay has elapsed. The timing diagrams in
Figure 18 and Figure 19 give a graphical representation of how
the ADM1085/ADM1086/ADM1087/ADM1088 enable outputs
respond to VIN and enable input signals.
Similarly, if the enable input is disabled while VIN is above the
threshold, the enable output deasserts immediately. Unlike VIN, a
low-to-high transition on ENIN (or high-to-low on ENIN) does
not yield a time delay on ENOUT (ENOUT).
CAPACITOR-ADJUSTABLE DELAY CIRCUIT
Figure 20 shows the internal circuitry used to generate the time
delay on the enable output. A 250 nA current source charges a
small internal parasitic capacitance, CINT. When the capacitor
voltage reaches 1.2 V, the enable output is asserted. The time
taken for the capacitor to reach 1.2 V, in addition to the propagation delay of the comparator, constitutes the enable timeout,
which is typically 35 µs.
Table 5. ADM1085/ADM1086 Truth Table
ENIN
0
1
0
1
ENOUT
0
0
0
1
To minimize the delay between VIN falling below VTH_FALLING and
the enable output de-asserting, an NMOS transistor is connected in parallel with CINT. The output of the voltage detector
is connected to the gate of this transistor so that, when VIN falls
below VTH_FALLING, the transistor switches on and CINT discharges
quickly.
Table 6. ADM1087/ADM1088 Truth Table
VIN
<VTH_FALLING
<VTH_FALLING
>VTH_RISING
>VTH_RISING
ENIN
ENOUT
1
0
1
0
1
1
1
0
VCC
250nA
SIGNAL FROM
VOLTAGE
DETECTOR
VIN
VTH_RISING
VTH_FALLING
CINT
1.2V
TO AND GATE
AND OUTPUT
STAGE
CEXT
C
ENOUT
tEN
04591-PrG-023
ENIN
Figure 18. ADM1085/ADM1086 Timing Diagram
VIN
VTH_RISING
Figure 20. Capacitor-Adjustable Delay Circuit
Connecting an external capacitor to the CEXT pin delays the
rise time—and therefore the enable timeout—further. The
relationship between the value of the external capacitor and the
resulting timeout is characterized by the following equation:
VTH_FALLING
tEN
04591-PrG-024
ENIN
ENOUT
04591-PrG-024
VIN
<VTH_FALLING
<VTH_FALLING
>VTH_RISING
>VTH_RISING
Figure 19. ADM1087/ADM1088 Timing Diagram
Rev. 0 | Page 9 of 16
tEN = (C × 4.8 ×106) + 35 µs
ADM1085/ADM1086/ADM1087/ADM1088
OPEN-DRAIN AND PUSH-PULL OUTPUTS
The ADM1085 and ADM1087 have open-drain output stages
that require an external pull-up resistor to provide a logic-high
voltage level. The geometry of the NMOS transistor enables the
output to be pulled up to voltage levels as high as 22 V.
The ADM1086 and ADM1088 have push-pull (CMOS) output
stages that require no external components to drive other logic
circuits. An internal PMOS pull-up transistor provides the
logic-high voltage level.
VCC (≤22V)
ADM1086/ADM1088
ADM1085/ADM1087
VCC
LOGIC
Figure 21. Open-Drain Output Stage
Figure 22. Push-Pull Output Stage
Rev. 0 | Page 10 of 16
04591-PrG-027
04591-PrG-026
LOGIC
ADM1085/ADM1086/ADM1087/ADM1088
APPLICATION INFORMATION
SEQUENCING CIRCUITS
In Figure 23, three ADM1085s are used to sequence four
supplies on power-up. Separate capacitors on the CEXT pins
determine the time delays between enabling of the 3.3 V, 2.5 V,
1.8 V, and 1.2 V supplies. Because the dc/dc converters and
ADM1085s are connected in cascade, and the output of any
converter is dependent on that of the previous one, an external
controller can disable all four supplies simultaneously by
disabling the first dc/dc converter in the chain.
The ADM1085/ADM1086/ADM1087/ADM1088 are
compatible with voltage regulators and dc-to-dc converters that
have active-high or active-low enable or shutdown inputs, with
a choice of open-drain or push-pull output stages. Figure 23 to
Figure 25 illustrate how each of the ADM1085/ADM1086/
ADM1087/ADM1088 simple sequencers can be used in
multiple-supply systems, depending on which regulators are
used and which output stage is preferred.
For power-down sequencing, an external controller dictates
when the supplies are switched off by accessing the ENIN
inputs individually.
12V
3.3V
DC/DC
OUT
3.3V
EN
3.3V
IN
DC/DC
OUT
ENABLE
CONTROL
OUT
ENIN
IN
DC/DC
OUT
1.2V
3.3V
VCC
VIN
ENOUT
ADM1085
CEXT
EN
1.8V
VCC
VIN
ENOUT
ADM1085
ENIN
DC/DC
3.3V
VCC
VIN
EN
2.5V
3.3V
3.3V
IN
ENOUT
ADM1085
CEXT
ENIN
CEXT
12V
3.3V
2.5V
1.8V
1.2V
tEN1
tEN2
tEN3
EXTERNAL
DISABLE
Figure 23. Typical ADM1085 Application Circuit
Rev. 0 | Page 11 of 16
04591-PrG-028
EN
IN
ADM1085/ADM1086/ADM1087/ADM1088
12V
EN
IN
DC/DC
OUT
EN
3.3V
IN
DC/DC
OUT
3.3V
OUT
ADM1086
ENIN
IN
DC/DC
OUT
1.2V
3.3V
VCC
VIN
ENOUT
ADM1086
CEXT
EN
1.8V
VCC
VIN
ENOUT
ENIN
IN
DC/DC
3.3V
VCC
VIN
EN
2.5V
ENOUT
ADM1086
CEXT
ENIN
CEXT
ENABLE
CONTROL
12V
3.3V
2.5V
1.8V
tEN1
tEN2
tEN3
04591-PrG-029
1.2V
EXTERNAL
DISABLE
Figure 24. Typical ADM1086 Application Circuit
12V
12V
OUT
SD
3.3V
IN
ADP3334
OUT
2.5V
SD
IN
ADP3334
OUT
3.3V
OUT
2.5V
VCC
VIN
ENOUT
ADM1087
ENIN
IN
ADP3334
3.3V
VCC
VIN
SD
3.3V
CEXT
ENOUT
ADM1088
Figure 25. Typical ADM1087 Application Circuit Using
ADP3334 Voltage Regulators
ENIN
CEXT
Figure 26. Typical ADM1088 Application Circuit Using
ADP3334 Voltage Regulators
Rev. 0 | Page 12 of 16
04591-PrG-031
IN
ADP3334
04591-PrG-030
SD
ADM1085/ADM1086/ADM1087/ADM1088
DUAL LOFO SEQUENCING
SIMULTANEOUS ENABLING
A power sequencing solution for a portable device, such as a
PDA, is shown in Figure 27. This solution requires that the
microprocessor’s power supply turn on before the LCD display
turns on, and that the LCD display power-down before the
microprocessor powers down. In other words, the last power
supply to turn on is the first one to turn off (LOFO).
The enable output can drive multiple enable or shutdown
regulator inputs simultaneously.
For the display power sequencing, the ADM1085 is equipped
with capacitor C2, which creates the delay between the microprocessor and display power turning on. When the system is
powered down, the ADM1085 turns off the display power
immediately, while the 3.3 V regulator waits for C1 to discharge
to 0.4 V before switching off.
9V
SYSTEM
POWER SWITCH
SD ADP3333 2.5V
MICROPROCESSOR
POWER
3.3V
SD
IN
ADP3333
OUT
SD
3.3V
IN
ADP3333
OUT
2.5V
3.3V
VCC
VIN
ENOUT
12V
ADM1085
ENIN
CEXT
SD
IN
ADP3333
OUT
1.8V
ENABLE
CONTROL
Figure 28. Enabling a Pair of Regulators from a Single ADM1085
POWER GOOD SIGNAL DELAYS
Sometimes sequencing is performed by asserting Power Good
signals when the voltage regulators are already on, rather than
sequencing the power supplies directly. In these scenarios, a
simple sequencer IC can provide variable delays so that
enabling separate circuit blocks can be staggered in time.
For example, in a notebook PC application, a dedicated
microcomputer asserts a Power Good signal for North Bridge™
and South Bridge™ ICs. The ADM1086 delays the south bridge’s
signal, so that it is enabled after the north bridge.
C1
9V
5V
3.3V
5V
9V
POWER_GOOD
EN
MICROCOMPUTER
ENOUT
SD ADP3333 5V
NORTH
BRIDGE
IC
DISPLAY
POWER
ADM1086
ENIN
CEXT
3.3V
C2
VIN
SYSTEM
POWER
9V
5V
ENOUT
EN
ADM1086
ENIN
0V
9V
CEXT
VC1
0V
Figure 29. Power Good Delay
2.5V
0V
5V
DISPLAY
POWER
0V
04591-PrG-032
MICROPROCESSOR
POWER
Figure 27. Dual LOFO Power-Supply Sequencing
Rev. 0 | Page 13 of 16
SOUTH
BRIDGE
IC
04591-PrG-034
VIN
04591-PrG-033
An RC network connects the battery and the SD input of the
ADP3333 voltage regulator. This causes power-up and powerdown transients to appear at the SD input when the battery is
connected and disconnected. The 3.3 V microprocessor supply
turns on quickly on power-up and turns off slowly on powerdown. This is due to two factors: Capacitor C1 charges up to 9 V
on power-up and charges down from 9 V on power-down, and
the SD pin has logic-high and logic-low input levels of 2 V and
0.4 V.
12V
ADM1085/ADM1086/ADM1087/ADM1088
QUAD-SUPPLY POWER GOOD INDICATOR
SEQUENCING WITH FET SWITCHES
The enable output of the simple sequencers is equivalent to an
AND function of VIN and ENIN. ENOUT is high only when the
voltage at VIN is above the threshold and the enable input
(ENIN) is high as well. Although ENIN is a digital input, it can
tolerate voltages as high as 22 V and can detect if a supply is
present. Therefore, a simple sequencer can monitor two supplies
and assert what can be interpreted as a Power Good signal
when both supplies are present. The outputs of two ADM1085s
can be wire-ANDed together to make a quad-supply Power
Good indicator.
The open-drain outputs of the ADM1085 and ADM1087 can
drive external FET transistors, which can switch on powersupply rails. All that is needed is a pull-up resistor to a voltage
source that is high enough to turn on the FET.
12V
3.3V
VIN
ADM1085
3.3V
3.3V
VIN
ENOUT
ENIN
POWER_GOOD
ADM1085
5V
2.5V
Figure 31. Sequencing with a FET Switch
ENIN
3.3V
2.5V
VIN
ENOUT
ENIN
04591-PrG-035
ADM1085
1.8V
CEXT
04591-PrG-036
9V
ENOUT
Figure 30. Quad-Supply Power Good Indicator
Rev. 0 | Page 14 of 16
ADM1085/ADM1086/ADM1087/ADM1088
OUTLINE DIMENSIONS
2.00 BSC
6
5
4
1
2
3
2.10 BSC
1.25 BSC
PIN 1
0.65 BSC
1.30 BSC
1.00
0.90
0.70
1.10 MAX
0.22
0.08
0.30
0.15
0.10 MAX
SEATING
PLANE
8°
4°
0°
0.46
0.36
0.26
0.10 COPLANARITY
COMPLIANT TO JEDEC STANDARDS MO-203AB
Figure 32. 6-Lead Plastic Surface-Mount Package [SC70]
(KS-6)
Dimensions shown in millimeters
ORDERING GUIDE
Model
ADM1085AKS-REEL7
Temperature Range
−40°C to +125°C
Quantity
3k
ADM1086AKS-REEL7
−40°C to +125°C
3k
ADM1087AKS-REEL7
−40°C to +125°C
3k
ADM1088AKS-REEL7
−40°C to +125°C
3k
Package Description
6-Lead Thin Shrink Small Outline
Transistor Package (SC70)
6-Lead Thin Shrink Small Outline
Transistor Package (SC70)
6-Lead Thin Shrink Small Outline
Transistor Package (SC70)
6-Lead Thin Shrink Small Outline
Transistor Package (SC70)
Rev. 0 | Page 15 of 16
Package Option
KS-6
Branding
M0V
KS-6
M0W
KS-6
M0X
KS-6
M0Y
ADM1085/ADM1086/ADM1087/ADM1088
NOTES
© 2004 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D04591–0–7/04(0)
Rev. 0 | Page 16 of 16