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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
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
a
ADM9261
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700 World Wide Web Site: http://www.analog.com
Fax: 617/326-8703 © Analog Devices, Inc., 1997
FEATURES
Simultaneous Monitoring of 9 V, and two 3.3 V Sup-
plies
Low Power: 10 µµ
µµ
µA Typical
Internal Comparator Hysteresis
Power Supply Glitch Immunity
VCC from 2.5 V to 3.6 V
Guaranteed from 10oC to +60oC
No External Components
8-Pin µµ
µµ
µSOIC Package
APPLICATIONS
Pagers
Portable Instruments
FUNCTIONAL BLOCK DIAGRAM
GND
SU1SU1
SU2SU2 ERR3ERR3
SU3SU3
11
22
33
44
88
77
66
55
ERR2ERR2
ERR1ERR1
VV
CCCC
C1
+
-
V
REF
ADM9261ADM9261
C2
C3
+
-
+
-
Triple- Power Supply Monitor
GENERAL DESCRIPTION
The ADM9261 is a Multi-Supply Monitor IC which si-
multaneously monitors the three power supply voltages of
a pager system and outputs error signals if any of the sup-
ply voltages falls below an acceptable minimum value.
Analog Devices experience in the design of power supply
supervisory circuits is used to provide an optimum solu-
tion for the overall circuit in terms of cost, performance
and power consumption. Key features of the design in-
clude the incorporation of hysteresis and glitch immunity
into the comparators, which minimizes the possibility of
spurious triggering by noise spikes on the supplies being
monitored. Power supply voltages outside V
CC
can be
monitored without the need for input attenuators or other
components, and the current drain (including input cur-
rents of the monitoring circuits) is typically only 10µA,
which imposes very little additional burden on the pager's
battery.
The ADM9261 is manufactured on one of Analog De-
vices proprietary BiCMOS processes, which also includes
high performance thin film resistors to achieve the accu-
racy required for the precision voltage reference and com-
parator trip points.
The ADM9261 is packaged in a space-saving µSOIC
package.
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ADM9261SPECIFICATIONS
Parameter Min Typ Max Units Test Conditions/Comments
OPERATING TEMPERATURE RANGE 10 60 °C
V
CC
SUPPLY VOLTAGE 2.5 3.6 V
TOTAL SUPPLY CURRENT 10 20 µA Total Current into V
CC
and
SU1 - SU3. Typ. is measured
with V
CC
= 3.3 V, SU1 = 6 V,
SU2 = SU3 = 3.3 V.
Max is measured with
V
CC
=3.6V, SU1 = 9 V,
SU2= SU3 = 3.6 V
V
CC
SUPPLY CURRENT 4 10 µA Current from SU1 - SU3 not
included
SU1 INPUT RESISTANCE 3 M ΩI
IN
~ 2 µA when SU1 = 6 V
SU2 INPUT RESISTANCE 1.65 M ΩI
IN
~ 2 µA when SU2 = 3.3 V
SU3 INPUT RESISTANCE 1.65 M ΩI
IN
~ 2 µA when SU3 = 3.3 V
SU1 LOW TRIP POINT 3.808 3.904 4.00 V Measured with SU1 Falling
SU2 LOW TRIP POINT 2.856 2.928 3.00 V Measured with SU2 Falling
SU3 LOW TRIP POINT 2.666 2.733 2.80 V Measured with SU3 Falling
HYSTERESIS 3 %
GLITCH IMMUNITY 20 µs 100 mV Glitch on V
CC
or SU1-3
PROPAGATION DELAY 20 µs Delay from Supply Going
Out side Tolerance until
Output Changes
OPEN DRAIN OUTPUT LOW 0.4 V 10 kΩ External to Positive Supply
V
CC
OPEN DRAIN OUTPUT HIGH V+ 0.25 V 10 kΩ External to Positive Supply
V
CC
Specifications subject to change without notice.
(VCC = Full Operating Range, TA = TMIN to TMAX unless otherwise noted)
ADM9261
3
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ORDERING GUIDE
Temperature Package
Model Range Option
1
ADM9261ARM 40°C to +85°C RM-8
ADM9261ARM-REEL
2
40°C to +85°C RM-8
ADM9261ARM-REEL7
3
40°C to +85°C RM-8
NOTES
1
RM = Thin Small Outline IC.
2
2500 devices per reel.
3
1000 devices per reel.
ABSOLUTE MAXIMUM RATINGS*
(T
A
= +25°C unless otherwise noted)
V
CC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 V to +6 V
SU1, SU2, SU3 . . . . . . . . . . . . . . . . . . . . 0.3 V to +15 V
All Other Inputs . . . . . . . . . . . . . . . 0.3 V to V
CC
+ 0.3 V
All Outputs . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 V to +6 V
Output Sink Current ERR1-3, . . . . . . . . . . . . . . . . 20 mA
Operating Temperature Range
Industrial (A Version) . . . . . . . . . . . . . 40°C to +85°C
Power Dissipation, RM-8 . . . . . . . . . . . . . . . TBD mW
θ
JA
Thermal Impedance . . . . . . . . . . . . . . . TBD°C/W
Lead Temperature (Soldering, 10 secs) . . . . . . . +300°C
Vapor Phase (60 secs) . . . . . . . . . . . . . . . . . . . . +215°C
Infrared (15 secs) . . . . . . . . . . . . . . . . . . . . . . . . +220°C
Storage Temperature Range . . . . . . . . . 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; functional
operation of the device at these or any other conditions above those listed
in the operational sections of this specification is not implied. Exposure to
absolute maximum ratings for extended periods of time may affect device
reliability.
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 the ADM9261 features proprietary ESD protection circuitry,
permanent damage may occur on devices subjected to high energy electrostatic dis-
charges. Therefore, proper ESD precautions are recommended to avoid performance
degradation or loss of functionality.
ADM9261
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PIN FUNCTION DESCRIPTIONS
Pin No. Mnemonic Function
1 GND Ground.
2 SU1 Supply to Be Monitored.
9 V battery supply - comparator trips when supply voltage falls below 4 V.
3 SU2 Supply to Be Monitored.
3.3 V supply - comparator trips when supply voltage falls below 3.0V
4 SU3 Supply to Be Monitored.
3.3 V supply. - comparator trips when supply voltage falls below 2.8V.
5V
CC
Supply Monitor IC Power Supply.
Can be powered from any power supply between 2.5 V and 3.6 V including one of the
supplies being monitored (except for SU1).
6ERR3 Open Drain Output.
Low when SU3 is below its minimum value. Otherwise pulls high through an external
10kΩ resistor to a positive supply.
7ERR2 Open Drain Output.
Low when SU2 is below its minimum value. Otherwise pulls high through an external
10kΩ resistor to a positive supply.
8ERR1 Open Drain Output.
Low when SU1 is below its minimum value. Otherwise pulls high through an external
10kΩ resistor to a positive supply.
PIN CONFIGURATION
GNDGND
SU1SU1
SU2SU2 ERR3ERR3
SU3SU3
11
22
33
44
88
77
66
55
TOP VIEWTOP VIEW
(Not to Scale)(Not to Scale)
ADM9261ADM9261
ERR2ERR2
ERR1ERR1
VV
CCCC
ADM9261
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CIRCUIT INFORMATION
Monitor Inputs SU1 to SU3
The ADM9621 is provided with three analog inputs, SU1
to SU3, to monitor supply voltages of +9 V and two
+3.3V supplies. Each input is connected to a voltage
comparator whose trip point is set by an on-chip voltage
reference and on-chip precision thin-film resistors. On-
chip attenuators reduce the input voltage to the compara-
tors, so that voltages greater than the supply voltage can
be monitored without the need for external resistors. As
the ADM9261 is intended for battery-powered systems,
the input attenuators are high resistance to minimise cur-
rent drawn from the supplies. This, coupled with the low-
pwer design of the comparators themselves, gives a typical
current consumption of 10µA, including the input currents
of SU1 to SU3.
Error Outputs
Error outputs ERR1 to ERR3 are open-drain outputs that
are OFF when the corresponding supply voltage SU1 to
SU3 is greater than its minimum value and ON when the
corresponding supply voltage falls below its minimum
value. Each output requires a 10kΩ pullup resistor to a
positive supply, which is normally the system logic supply,
but can be different if required. The open-drain construc-
tion allows two or more of these outputs to be wire
ANDed together if required, as shown in figure 1.
SU1
10kW
V
CC
SU2
SU3 ERR3
ERR1
ERR2
V
CC
GND
OUTPUT
Truth Table for Wired AND
SU1 SU2 SU 3 Output
< min < min < min 0
< min < min > min 0
< min > min < min 0
< min > min > min 0
> min < min < min 0
> min < min > min 0
> min > min < min 0
> min > min > min 1
Power Supply V
CC
The ADM9261 can be powered from any supply voltage
between 2.5 V and 6 V. This includes any of the supply
voltages apart from that connected to SU1, since this is
greater than 6 V. It will usually be powered from one of
the 3.3 V supplies.
The logic outputs are open-drain and take their output
high level from the voltage connected to the pull-up resis-
tor. They will normally be connected to V
CC
, but can be
connected to any voltage up to 15V if a different logic
swing is required.
ADM9261
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APPLICATIONS
The ADM9261 is designed for use in pagers and other
portable devices that use 3.3V logic systems derived from
a 9V battery. Interfacing of the ADM9261 to the system
will vary with the application, if a microcontroller is used,
the outputs of the ADM9261 may be connected to one or
more I/O lines. If a microprocessor is used with a separate
ASIC or other chip for I/O then the ADM9261 can be
SU1
10kW
V
CC
PAGER
ASIC MICROPROCESSOR
SU2
10kW
V
CC
SU3
10kW
V
CC
PSU #1
9V
PSU #2
3.3V
PSU #3
3.3V ERR3
ERR1
ERR2
V
CC
GND
ADM9261
Figure 14. Typical Application of ADM9261
interfaced to this. In either case the ADM9261 is very
simple to use. Inputs SU1 to SU3 are simply connected to
the supplies to be monitored and the outputs are con-
nected to the devices logic system, either separately or to a
single input using wired AND. The ADM9261 will derive
its power supply from one of the 3.3V supplies.
Figure 14 shows a typical application of the ADM9261.
ADM9261
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OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
8-Lead Micro SOIC
(R-8A)
85
4
1
0.122 (3.10)
0.114 (2.90)
0.199 (5.05)
0.187 (4.75)
PIN 1
0.0256 (0.65) BSC
0.122 (3.10)
0.114 (2.90)
SEATING
PLANE
0.006 (0.15)
0.002 (0.05)
0.018 (0.46)
0.008 (0.20)
0.043 (1.09)
0.037 (0.94)
0.120 (3.05)
0.112 (2.84)
0.011 (0.28)
0.003 (0.08)
0.028 (0.71)
0.016 (0.41)
33°
27°
0.120 (3.05)
0.112 (2.84)