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FEATURES
Precision Supply Voltage Monitor
+5 V, +3.3 V, +3 V Power Supply Monitor
35 A Quiescent Current
140 ms (min) Power-On Reset Pulse
Low Cost
8-Pin DIP/SO Packages
Upgrade for MAX709
APPLICATIONS
Microprocessor Systems
Computers
Controllers
Intelligent Instruments
Critical P Monitoring
Automotive Systems
Critical P Power Monitoring
GENERAL DESCRIPTION
V
CC
V
TH
Power Supply Monitor
with Reset
ADM709
FUNCTIONAL BLOCK DIAGRAM
ADM709
RESET
GENERATOR
RESET
GND
V
CC
V
CC
ADM709
RESET
GND
RESET
µP
GND
The ADM709 contains a power supply monitor which generates
a system reset during power-up, power-down and brownout
conditions. When V
CC
falls below the reset threshold,
RESET
goes low and holds the
µP
in reset. On power-up the
RESET
output is held low for 140 ms after V
CC
rises above the thresh-
old. The
RESET
output remains operational with V
CC
as low
as 1 V.
Three supply-voltage threshold levels are available suitable for
+5 V, +3.3 V and for +3 V supply monitoring. The actual reset
voltage threshold is given below.
The ADM709 is available in 8-pin DIP and SOIC packages.
Table I. Reset Threshold
Typical Operating Circuit
ORDERING GUIDE
Model
ADM709LAN
ADM709LAR
ADM709MAN
ADM709MAR
ADM709TAN
ADM709TAR
ADM709SAN
ADM709SAR
ADM709RAN
ADM709RAR
Reset
Threshold
4.65 V
4.65 V
4.40 V
4.40 V
3.08 V
3.08 V
2.93 V
2.93 V
2.63 V
2.63 V
Temperature
Range
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
Package
Option*
N-8
SO-8
N-8
SO-8
N-8
SO-8
N-8
SO-8
N-8
SO-8
Suffix
L
M
T
S
R
Voltage (V)
4.65
4.40
3.08
2.93
2.63
*N = Plastic DIP; SO = SOIC.
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
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
© Analog Devices, Inc., 1995
One Technology Way, P.O. Box 9106, Norwood. MA 02062-9106, U.S.A.
Tel: 617/329-4700
Fax: 617/326-8703
ADM709–SPECIFICATIONS
(V
Parameter
V
CC
Operating Voltage Range
Supply Current
Min
1.0
1.2
35
35
65
65
4.5
4.25
3.00
2.85
2.55
4.65
4.40
3.08
2.93
2.63
20
140
280
Typ
CC
= Full Operating Range, T
A
= T
MIN
to T
MAX
unless otherwise noted)
Max
5.5
5.5
85
110
150
200
4.75
4.50
3.15
3.00
2.70
Units
V
V
µA
µA
µA
µA
V
V
V
V
V
µs
380
0.3
0.4
0.3
0.4
ms
V
V
V
V
V
V
Test Conditions/Comments
T
A
= 0°C to +70°C
T
A
= –40°C to +85°C
V
CC
< 3.6 V, T
A
= 0°C to +70°C
V
CC
< 3.6 V, T
A
= –40°C to +85°C
V
CC
< 5.5 V, T
A
= 0°C to +70°C
V
CC
< 5.5 V, T
A
= –40°C to +85°C
ADM709L
ADM709M
ADM709T
ADM709S
ADM709R
V
CC
= Reset Threshold max–min
V
CC
= Reset Threshold max, V
CC
Rising
ADM709R/S/T, I
SINK
= 1.2 mA. V
CC
= Reset
Threshold min
ADM709L/M, I
SINK
= 3.2 mA. V
CC
= Reset
Threshold min
I
SINK
= 50
µA.
V
CC
≥
1.0 V
I
SINK
= 100
µA.
V
CC
≥
1.2 V
ADM709R/S/T, I
SOURCE
= 500
µA,
V
CC
≥
Reset
Threshold max
ADM709L/M, I
SOURCE
= 800
µA,
V
CC
≥
Reset
Threshold max
Reset Threshold
V
CC
to
RESET
Delay
RESET
Active Time-Out Period
RESET
Output Voltage
0.8 ×
V
CC
V
CC
–1.5 V
Specifications subject to change without notice.
ABSOLUTE MAXIMUM RATINGS*
(T
A
= +25°C unless otherwise noted)
PIN FUNCTION DESCRIPTION
V
CC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +6 V
RESET
Output . . . . . . . . . . . . . . . . . . . –0.3 V to V
CC
+ 0.3 V
V
CC
Input Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 mA
RESET
Output Current . . . . . . . . . . . . . . . . . . . . . . . . 20 mA
Power Dissipation, N-8 DIP . . . . . . . . . . . . . . . . . . . . 727 mW
θ
JA
Thermal Impedance . . . . . . . . . . . . . . . . . . . . . 135°C/W
Power Dissipation, SO-8 SOIC . . . . . . . . . . . . . . . . . . 470 mW
θ
JA
Thermal Impedance . . . . . . . . . . . . . . . . . . . . . 110°C/W
Operating Temperature Range
Industrial ( A Version) . . . . . . . . . . . . . . . . . –40°C to +85°C
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
ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . >5 kV
*
Mnemonic Pin No.
NC
V
CC
RESET
1, 4, 5, 6, 8
2
7
Function
No Connect Pins.
+5 V, +3.3 V, +3 V Power Supply
Input.
Logic Output. It remains low while
V
CC
is below the reset threshold
voltage and for 280 ms (typ) after
V
CC
rises above the threshold.
Ground, 0 V.
GND
3
PIN CONFIGURATION
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 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.
NC
1
V
CC 2
GND
3
NC
4
8
NC
RESET
NC
NC
ADM709
TOP VIEW
(Not to Scale)
7
6
5
NC = NO CONNECT
–2–
REV. 0
ADM709
ADM709
V
CC
V
TH
RESET
GENERATOR
RESET
RESET
at Voltages < 1 V
GND
The ADM709
RESET
output is guaranteed to operate with
supply voltages as low as 1 V. If it is desired that the
RESET
output remains low below 1 V, then a pull-down resistor should
be connected between the
RESET
output and GND. A resistor
of 100 kΩ is suitable. This is illustrated in Figure 5.
Figure 1. Functional Block Diagram
ADM709
RESET
V
CC
V
CC
R1
GND
ADM709
RESET
GND
RESET
µP
GND
Figure 5.
RESET
Valid @ V
CC
< 1 V
Glitch Immunity
Figure 2. Typical Operating Circuit
CIRCUIT INFORMATION
RESET
Output
The ADM709 is immune to short transients which may occur
on the V
CC
line. This is important so that spurious resets are not
generated as a result of minor glitches on the power supply.
Additional glitch immunity may be obtained by connecting a
capacitor (0.1
µF
or greater) as close as possible to the V
CC
pin
on the device.
Microprocessors with Bidirectional I-O
RESET
is an active low output which provides a reset signal to
the microprocessor whenever the V
CC
supply voltage is below
the reset threshold. An internal timer holds
RESET
low for
140 ms after the voltage on V
CC
rises above the threshold. This
is intended as a power-on reset signal for the processor. It allows
time for the power supply and microprocessor to stabilize after
power up. Similarly a power supply brownout will initiate a pro-
cessor reset. On power-down, the
RESET
output remains low
with V
CC
as low as 1 V. This ensures that the microprocessor is
held in a stable shutdown condition as the power supply drops.
VRT
VRT
Some microprocessors or microcontrollers such as the
MC68HC11 have bidirectional reset lines. In order to avoid
signal contention, a resistor of 4.7 kΩ should be connected
between the ADM709
RESET
output and the microcontroller
RESET
line. This arrangement is shown in Figure 6.
+5V
BUFFERED
RESET
V
CC
V
CC
ADM709
t
RS
RESET
µP
RESET
RESET
GND
GND
Figure 3. Power Off/On
RESET
Timing
Figure 6. Interfacing to Microprocessors with
Bidirectional
RESET
V
CC
RESET
400ms/DIV
Figure 4.
RESET
Output vs. V
CC
REV. 0
–3–
ADM709
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
8-Lead Plastic DIP
(N-8)
C2022–18–4/95
0.195 (4.95)
0.115 (2.93)
8
PIN 1
1
5
0.280 (7.11)
0.240 (6.10)
4
0.430 (10.92)
0.348 (8.84)
0.210
(5.33)
MAX
0.160 (4.06)
0.115 (2.93)
0.060 (1.52)
0.015 (0.38)
0.325 (8.25)
0.300 (7.62)
0.130
(3.30)
MIN
SEATING
PLANE
0.015 (0.381)
0.008 (0.204)
0.022 (0.558)
0.014 (0.356)
0.100
(2.54)
BSC
0.070 (1.77)
0.045 (1.15)
8-Lead SOIC
(SO-8)
8
5
0.1574 (4.00)
0.1497 (3.80)
PIN 1
1
4
0.2440 (6.20)
0.2284 (5.80)
0.1968 (5.00)
0.1890 (4.80)
0.0098 (0.25)
0.0040 (0.10)
0.0500
(1.27)
BSC
0.0688 (1.75)
0.0532 (1.35)
0.0192 (0.49)
0.0138 (0.35)
8
°
0
°
0.0196 (0.50)
x 45
°
0.0099 (0.25)
0.0098 (0.25)
0.0075 (0.19)
0.0500 (1.27)
0.0160 (0.41)
–4–
REV. 0
PRINTED IN U.S.A.
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