ANALOG DEVICES ADM708 Service Manual
Low Cost Microprocessor
www.BDTIC.com/ADI
FEATURES
Guaranteed
190 μA quiescent current
Precision supply voltage monitor
4.65 V (ADM705/ADM707)
4.40 V (ADM706/ADM708)
200 ms reset pulse width
Debounced TTL/CMOS manual reset input (
Independent watchdog timer (ADM705/ADM706)
1.60 sec timeout (ADM705/ADM706)
Active high reset output (ADM707/ADM708)
Voltage monitor for power-fail or low battery warning
Superior upgrade for MAX705 to MAX708
APPLICATIONS
Microprocessor systems
Computers
Controllers
Intelligent instruments
Critical microprocessor supply monitoring
valid with VCC = 1 V
RESET
MR
)
Supervisory Circuits
ADM705/ADM706/ADM707/ADM708
FUNCTIONAL BLOCK DIAGRAMS
WATCHDOG
INPUT (WDI)
V
POWER-FAIL
INPUT (PFI)
V
POWER-FAIL
INPUT (PFI)
WATCHDOG
TRANSITION
DETECTOR
V
CC
250μA
MR
CC
4.65V*
1.25V
*
VOLTAGE REFERENCE = 4.65V (ADM705), 4.40V (ADM 706)
Figure 1. ADM705/ADM706
V
CC
250μA
MR
CC
4.65V*
1.25V
WATCHDOG
TIMER
RESET AND
WATCHDOG
TIMEBASE
RESET
GENERATOR
ADM705/
ADM706
RESET
GENERATOR
ADM707/
ADM708
WATCHDOG
OUTPUT (WDO)
RESET
POWER-FAIL
OUTPUT (PFO)
RESET
RESET
POWER-FAIL
OUTPUT (PFO)
00088-001
GENERAL DESCRIPTION
The ADM705/ADM706/ADM707/ADM708 microprocessor
supervisory circuits are suitable for monitoring 5 V power
supplies/batteries and can also monitor microprocessor activity.
The ADM705/ADM706 provide power-supply monitoring
circuitry that generate a reset output during power-up, powerdown, and brownout conditions. The reset output remains
operational with V
monitoring circuitry is also provided. This is activated if the
watchdog input has not been toggled within 1.60 seconds.
In addition, there is a 1.25 V threshold detector to warn of
power-failures, to detect low battery conditions, or to monitor an
additional power supply. An active low, debounced manual reset
MR
input (
) is also included.
as low as 1 V. Independent watchdog
CC
* VOLTAGE REFERENCE = 4.65V (ADM707), 4.40V (ADM708)
Figure 2. ADM707/ADM708
The ADM705 and ADM706 are identical except for the reset
threshold monitor levels, which are 4.65 V and 4.40 V, respectively.
The ADM707 and ADM708 provide a similar functionality to
the ADM705 and ADM706 and only differ in that a watchdog
timer function is not available. Instead, an active high reset
output (RESET) is available as well as the active low reset output
RESET
(
). The ADM707 and ADM708 are identical except for
the reset threshold monitor levels, which are 4.65 V and 4.40 V,
respectively.
All parts are available in narrow 8-lead PDIP and 8-lead SOIC
packages.
00088-002
Rev. G
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 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.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 www.analog.com
Fax: 781.461.3113 ©2008 Analog Devices, Inc. All rights reserved.
ADM705/ADM706/ADM707/ADM708
www.BDTIC.com/ADI
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Functional Block Diagrams ............................................................. 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Specifications ..................................................................................... 3
Absolute Maximum Ratings ............................................................ 4
ESD Caution .................................................................................. 4
Pin Configurations and Function Descriptions ........................... 5
Typical Performance Characteristics ............................................. 6
Circuit Information .......................................................................... 8
REVISION HISTORY
3/08—Rev. F to Rev. G
Changes to Applications .................................................................. 1
Changes to Table 2 ............................................................................ 4
Changes to Figure 9 .......................................................................... 6
Changes to Figure 10, Figure 11, and Figure 12 ........................... 7
Changes to Figure 14 ........................................................................ 8
Changes to Ordering Guide .......................................................... 12
2/07—Rev. E to Rev. F
Updated Format .................................................................. Universal
Changes to Watchdog Timeout Period .......................................... 3
Replaced Pin Configurations and Function Descriptions
Section ................................................................................................ 5
7/06—Rev. D to Rev. E
Added RM-8 (MSOP) Package ......................................... Universal
Changes to Table 2 ............................................................................ 4
Updated Outline Dimensions ....................................................... 12
Changes to Ordering Guide .......................................................... 12
Power-Fail
Manual Reset ..................................................................................8
Watchdog Timer (ADM705/ADM706) .....................................8
Power-Fail Comparator ................................................................8
Va l id
Applications Information .............................................................. 10
Monitoring Additional Supply Levels ...................................... 10
Microprocessor with Bidirectional RESET ............................. 10
Outline Dimensions ....................................................................... 11
Ordering Guide .......................................................................... 12
11/05—Rev. C to Rev. D
Updated Format .................................................................. Universal
Deleted Figure 2 ................................................................................. 4
Updated Outline Dimensions ....................................................... 11
Changes to Ordering Guide .......................................................... 12
8/02—Rev. B to Rev. C
Removed RM-8 (μSOIC) Package .................................... Universal
Updated N-8 and R-8 Packages ....................................................... 8
RESET
Output ...........................................................8
RESET
Below 1 V VCC ........................................................9
Rev. G | Page 2 of 12
ADM705/ADM706/ADM707/ADM708
www.BDTIC.com/ADI
SPECIFICATIONS
VCC = 4.75 V to 5.5 V, TA = T
Table 1.
Parameter Min Typ Max Unit Test Conditions/Comments
POWER SUPPLY
VCC Operating Voltage Range 1.0
Supply Current
LOGIC OUTPUT
Reset Threshold 4.5 4.65 4.75 V ADM705/ADM707
Reset Threshold Hysteresis
RESET PULSE WIDTH 160 200 280 ms
RESET OUTPUT VOLTAGE
RESET OUTPUT VOLTAGE VCC − 1.5
WATCHDOG TIMEOUT PERIOD (tWD) 1.00 1.60 2.25 sec VIL = 0.4 V, VIH = VCC × 0.8, WDI = VCC
WDI Pulse Width (t
WATCHDOG INPUT
WDI Input Threshold
Logic Low
Logic High 3.5
WDI Input Current
) 50
WP
WDO OUTPUT VOLTAGE
MANUAL RESET INPUT
MR Pull-Up Current
MR Pulse Width
MR INPUT THRESHOLD
Logic Low
Logic High
MR TO RESET OUTPUT DELAY
POWER-FAIL INPUT
PFI Input Threshold 1.2 1.25 1.3 V
PFI Input Current −25 +0.01 +25 nA
PFO OUTPUT VOLTAGE
MIN
to T
, unless otherwise noted.
MAX
4.25 4.40 4.50 V ADM706/ADM708
VCC − 1.5
−150 −50
VCC − 1.5
100 250 600 μA
150
2.0
V
− 1.5
CC
190 250 μA
40
5.5 V
mV
0.4 V I
0.3 V VCC = 1 V, I
0.3 V VCC = 1.2 V, I
0.4 V ADM707/ADM708, I
V I
V ADM707/ADM708, I
ns
SOURCE
= 3.2 mA
SINK
= 800 μA
0.8 V
50 150 μA WDI = 0 V
0.4 V I
0.8 V
250 ns
V
μA WDI = 0 V
V I
ns
V
SOURCE
= 1.2 mA
SINK
= 0 V
MR
= 800 μA
0.4 V I
V I
= 800 μA
SOURCE
= 3.2 mA
SINK
= 50 μA
SINK
SINK
= 100 μA
SOURCE
SINK
= 800 μA
= 1.2 mA
Rev. G | Page 3 of 12
ADM705/ADM706/ADM707/ADM708
www.BDTIC.com/ADI
ABSOLUTE MAXIMUM RATINGS
TA = 25°C, unless otherwise noted.
Table 2.
Parameter Rating
VCC −0.3 V to +6 V
All Other Inputs −0.3 V to VCC + 0.3 V
Input Current
VCC 20 mA
GND 20 mA
Digital Output Current 20 mA
Power Dissipation, N-8 PDIP 727 mW
θJA Thermal Impedance 135°C/W
Power Dissipation, R-8 SOIC 470 mW
θJA Thermal Impedance 110°C/W
Power Dissipation, RM-8 MSOP 900 mW
θJA Thermal Impedance 206°C/W
Operating Temperature Range
Industrial (Version A) −40°C to +85°C
Lead Temperature (Soldering, 10 sec) 300°C
Vapor Phase (60 sec) 215°C
Infrared (15 sec) 220°C
Storage Temperature Range −65°C to +150°C
ESD Rating >4.5 kV
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 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
Rev. G | Page 4 of 12
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