Datasheet ADM709TAR, ADM709TAN, ADM709SAR, ADM709SAN, ADM709RAR Datasheet (Analog Devices)

Power Supply Monitor

a

FEATURES
Precision Supply Voltage Monitor
+5 V, +3.3 V, +3 V Power Supply Monitor
35 mA 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 mP Monitoring
Automotive Systems
Critical mP Power Monitoring

GENERAL DESCRIPTION

The ADM709 contains a power supply monitor which generates
a system reset during power-up, power-down and brownout
conditions. When V
goes low and holds the µP in reset. On power-up the
output is held low for 140 ms after V
old. The

RESET output remains operational with VCC 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.

falls below the reset threshold, RESET

CC

rises above the thresh-

CC

Table I. Reset Threshold

Suffix Voltage (V)

L 4.65
M 4.40
T 3.08
S 2.93
R 2.63

RESET

with Reset

ADM709

FUNCTIONAL BLOCK DIAGRAM

V

CC

V

TH

Typical Operating Circuit

Reset Temperature Package

Model Threshold Range Option*

ADM709LAN 4.65 V –40°C to +85°C N-8
ADM709LAR 4.65 V –40°C to +85°C SO-8
ADM709MAN 4.40 V –40°C to +85°C N-8
ADM709MAR 4.40 V –40°C to +85°C SO-8
ADM709TAN 3.08 V –40°C to +85°C N-8
ADM709TAR 3.08 V –40°C to +85°C SO-8
ADM709SAN 2.93 V –40°C to +85°C N-8
ADM709SAR 2.93 V –40°C to +85°C SO-8
ADM709RAN 2.63 V –40°C to +85°C N-8
ADM709RAR 2.63 V –40°C to +85°C SO-8

*N = Plastic DIP; SO = SOIC.

ADM709

RESET

GENERATOR

GND

V

CC

ADM709

RESET

GND GND

ORDERING GUIDE

RESET

RESET

V

CC

µP

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: [phone] Fax: [phone]

ADM709–SPECIFICATIONS

(VCC = Full Operating Range, TA = T

MIN

to T

unless otherwise noted)

MAX

Parameter Min Typ Max Units Test Conditions/Comments

V

Operating Voltage Range 1.0 5.5 V T

CC

1.2 5.5 V T

Supply Current 35 85 µAV

35 110 µAV
65 150 µAV
65 200 µAV

= 0°C to +70°C

A

= –40°C to +85°C

A

< 3.6 V, T

CC

< 3.6 V, T

CC

< 5.5 V, T

CC

< 5.5 V, T

CC

= 0°C to +70°C

A

= –40°C to +85°C

A

= 0°C to +70°C

A

= –40°C to +85°C

A

Reset Threshold 4.5 4.65 4.75 V ADM709L

4.25 4.40 4.50 V ADM709M

3.00 3.08 3.15 V ADM709T

2.85 2.93 3.00 V ADM709S

2.55 2.63 2.70 V ADM709R

V

to RESET Delay 20 µsV

CC

= Reset Threshold max–min

CC

RESET Active Time-Out Period 140 280 380 ms VCC = Reset Threshold max, VCC Rising

RESET Output Voltage 0.3 V ADM709R/S/T, I

Threshold min

0.4 V ADM709L/M, I
Threshold min

0.8 × V

CC

0.3 V I

0.4 V I

V ADM709R/S/T, I

= 50 µA. VCC ≥ 1.0 V

SINK

= 100 µA. VCC ≥ 1.2 V

SINK

Threshold max

V

–1.5 V V ADM709L/M, I

CC

Threshold max

Specifications subject to change without notice.

ABSOLUTE MAXIMUM RATINGS*

(TA = +25°C unless otherwise noted)

VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +6 V

RESET Output . . . . . . . . . . . . . . . . . . . –0.3 V to VCC + 0.3 V

V

Input Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 mA

CC

RESET Output Current . . . . . . . . . . . . . . . . . . . . . . . . 20 mA

Mnemonic Pin No. Function

NC 1, 4, 5, 6, 8 No Connect Pins.

V

CC

PIN FUNCTION DESCRIPTION

2 +5 V, +3.3 V, +3 V Power Supply

Power Dissipation, N-8 DIP . . . . . . . . . . . . . . . . . . . . 727 mW

θ

Thermal Impedance . . . . . . . . . . . . . . . . . . . . . 135°C/W

JA

Power Dissipation, SO-8 SOIC . . . . . . . . . . . . . . . . . .470 mW

θ

Thermal Impedance . . . . . . . . . . . . . . . . . . . . . 110°C/W

JA

RESET 7 Logic Output. It remains low while

Operating Temperature Range

Industrial ( A Version) . . . . . . . . . . . . . . . . . –40°C to +85°C

Lead Temperature (Soldering, 10 secs) . . . . . . . . . . . . +300°C

GND 3 Ground, 0 V.

Vapor Phase (60 secs) . . . . . . . . . . . . . . . . . . . . . . . . . +215°C

Infrared (15 secs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +220°C

Storage Temperature Range . . . . . . . . . . . . .–65°C to +150°C

ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .>5 kV

*

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.

PIN CONFIGURATION

1

NC

2

V

GND

NC

ADM709

CC

TOP VIEW

3

(Not to Scale)

4

NC = NO CONNECT

= 1.2 mA. VCC = Reset

SINK

= 3.2 mA. VCC = Reset

SINK

= 500 µA, VCC ≥ Reset

SOURCE

= 800 µA, VCC ≥ Reset

SOURCE

Input.

V

is below the reset threshold

CC

voltage and for 280 ms (typ) after
VCC rises above the threshold.

8

NC

7

RESET

6

NC

5

NC

–2–

REV. 0

ADM709

R1

RESET

ADM709

GND

RESET

ADM709

GND GND

µP

BUFFERED

RESET

+5V

RESET

V

CC

V

CC

V

TH

ADM709

GND

RESET

GENERATOR

RESET

Figure 1. Functional Block Diagram

V

CC

ADM709

RESET

GND GND

RESET

V

CC

µP

Figure 2. Typical Operating Circuit

CIRCUIT INFORMATION RESET Output

RESET is an active low output which provides a reset signal to
the microprocessor whenever the V
the reset threshold. An internal timer holds
140 ms after the voltage on V

CC

supply voltage is below

CC

RESET low for

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 pro­cessor reset. On power-down, the
with V

as low as 1 V. This ensures that the microprocessor is

CC

RESET output remains low

held in a stable shutdown condition as the power supply drops.

RESET at Voltages < 1 V

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 5.

RESET

Valid @ V

CC

< 1 V

Glitch Immunity

The ADM709 is immune to short transients which may occur
on the V

line. This is important so that spurious resets are not

CC

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

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.

V

CC

RESET

Figure 3. Power Off/On

V

CC

RESET

Figure 4.

REV. 0

VRT VRT

RESET

t

RS

RESET

400ms/DIV

Output vs. V

Timing

CC

–3–

Figure 6. Interfacing to Microprocessors with
Bidirectional

RESET

ADM709

PIN 1

0.210

(5.33)

MAX

0.160 (4.06)

0.115 (2.93)

0.022 (0.558)

0.014 (0.356)

OUTLINE DIMENSIONS

Dimensions shown in inches and (mm).

8-Lead Plastic DIP

(N-8)

58

0.280 (7.11)

0.240 (6.10)

0.100
(2.54)

BSC

4

0.070 (1.77)

0.045 (1.15)

0.060 (1.52)

0.015 (0.38)

0.130
(3.30)
MIN

SEATING
PLANE

0.325 (8.25)

0.300 (7.62)

0.015 (0.381)

0.008 (0.204)

1

0.430 (10.92)

0.348 (8.84)

8-Lead SOIC

(SO-8)

0.195 (4.95)

0.115 (2.93)

C2022–18–4/95

0.0098 (0.25)

0.0040 (0.10)

PIN 1

8

1

0.1968 (5.00)

0.1890 (4.80)

0.0500
(1.27)

BSC

5

4

0.0192 (0.49)

0.0138 (0.35)

0.1574 (4.00)

0.1497 (3.80)

0.2440 (6.20)

0.2284 (5.80)

0.0688 (1.75)

0.0532 (1.35)

0.0098 (0.25)

0.0075 (0.19)

8

°

0

°

0.0196 (0.50)

0.0099 (0.25)

0.0500 (1.27)

0.0160 (0.41)

x 45

°

–4–

PRINTED IN U.S.A.

REV. 0