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.
a
Microprocessor
Supervisory Circuits
ADM8698/ADM8699
FUNCTIONAL BLOCK DIAGRAM
RESET
GENERATOR
4.65V
V
CC
WATCHDOG
INPUT
WDI
*
ADM8698/
ADM8699
RESET
WATCHDOG
OUTPUT
WDO
*
RESET
*
*
WDI (ADM8699 ONLY)
RESET (SOIC ONLY)
WDO
(ADM8699 SOIC ONLY)
WATCHDOG
TRANSITION DETECTOR
(1 sec)
TYPICAL APPLICATION CIRCUIT
*
ADM8699 ONLY
+5V
V
CC
WDI
*
GND
ADM8698/
ADM8699
RESET
P POWER
P SYSTEM
I/O LINE
P RESET
FEATURES
Superior Upgrade for ADM698/ADM699, MAX698/MAX699
Guaranteed
RESET Assertion with V
CC
= 1 V
Low 70 A Supply Current
Precision 4.65 V Voltage Monitor
Power OK/Reset Time Delay
Watchdog Timer
Minimum Component Count
Performance Specified over Temperature
APPLICATIONS
Microprocessor Systems
Computers
Controllers
Intelligent Instruments
Automotive Systems
Critical P Power Monitoring
GENERAL DESCRIPTION
The ADM8698/ADM8699 supervisory circuits provide power
supply monitoring and watchdog timing for microprocessor
systems.
The ADM8698 monitors the 5 V V
CC
power supply and gener-
ates a
RESET pulse during power up, power down and during
low voltage "Brown Out" conditions. The
RESET output is
guaranteed to be functional (logic low) with V
CC
as low as 1 V.
The ADM8699 features an identical monitoring circuit as in the
ADM8698, plus an additional watchdog timer input to monitor
microprocessor activity. The
RESET output is forced low if the
watchdog input is not toggled within the 1 second watchdog
timeout period.
Both parts are available in 8-pin plastic DIP/SOIC and 16-lead
SOIC packages. The 16-lead SOIC contains additional out-
puts
RESET (without inversion) and Watchdog Output WDO
(ADM8699 only).
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
REV. 0
2
ORDERING GUIDE
Temperature
Package
Model
Range
Options*
ADM8698AN
40
C to +85
C
N-8
ADM8698ARW
40
C to +85
C
R-16
ADM8698ARN
40
C to +85
C
R-8
ADM8699AN
40
C to +85
C
N-8
ADM8699ARW
40
C to +85
C
R-16
ADM8699ARN
40
C to +85
C
R-8
*N = Plastic DIP; R = Small Outline.
ABSOLUTE MAXIMUM RATINGS*
(T
A
= +25
C unless otherwise noted)
V
CC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 V to +6 V
All Other Inputs . . . . . . . . . . . . . . . . . . . 0.3 V to V
CC
+ 0.3 V
Power Dissipation 8-Pin DIP . . . . . . . . . . . . . . . . . . . . 500 mW
JA
, Thermal Impedance . . . . . . . . . . . . . . . . . . . . +120
C/W
Power Dissipation 16-Pin SOIC . . . . . . . . . . . . . . . . . 375 mW
JA
, Thermal Impedance . . . . . . . . . . . . . . . . . . . . +110
C/W
Power Dissipation 8-Pin SOIC . . . . . . . . . . . . . . . . . . 500 mW
JA
, Thermal Impedance . . . . . . . . . . . . . . . . . . . . +125
C/W
Operating Temperature Range
Industrial (A Version) . . . . . . . . . . . . . . . . . 40
C to +85
C
Storage Temperature Range . . . . . . . . . . . . . 65
C to +150
C
Lead Temperature (Soldering, 10 secs) . . . . . . . . . . . . +300
C
Vapor Phase (60 secs) . . . . . . . . . . . . . . . . . . . . . . . +215
C
Infrared (15 secs) . . . . . . . . . . . . . . . . . . . . . . . . . . . +220
C
ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . >4 kV
*Stresses above those listed under Absolute Maximum Ratings may cause perma-
nent 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.
(V
CC
= +5 V 10%, T
A
= T
MIN
to T
MAX
unless otherwise noted)
ADM8698/ADM8699SPECIFICATIONS
Parameter
Min
Typ
Max
Units
Test Conditions/Comments
V
CC
Operating Voltage Range
3.0
5.5
V
Supply Current
70
100
A
Power-Down Reset Assertion
4.5
4.65
4.75
V
Power-Up Reset Deassertion
Reset Threshold Hysteresis
40
mV
Reset Active Time
140
200
280
ms
Watchdog Timeout Period (ADM8699)
1.0
1.6
2.25
s
Minimum WDI Input Pulse Width
50
ns
V
IL
= 0.4, V
IH
= 0.8 (V
CC
)
RESET Output Voltage
0.4
V
I
SINK
= 3.2 mA, V
CC
= 4.4 V
RESET Output Voltage (V
CC
= 1 V)
12
200
mV
I
SINK
= 100
A, V
CC
= 1.0 V
3.5
V
I
SOURCE
= 500
A, V
CC
= 5 V
RESET and WDO Output Voltage
0.4
V
I
SINK
= 3.2 mA, V
CC
= 5 V
3.5
V
I
SOURCE
= 1
A, V
CC
= 4.4 V
RESET Output Short Circuit Current
45
mA
Output Sink Current
WDI Input Threshold (ADM8699)
Logic Low
0.8
V
Logic High
3.5
V
WDI Input Current
+1
+10
A
WDI = V
CC
10
1
A
WDI = 0 V
Specifications subject to change without notice.
ADM8698/ADM8699
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3
PIN FUNCTION DESCRIPTIONS
Mnemonic
Function
V
CC
+5 V Power Supply Input.
GND
0 V. Ground reference for all signals.
RESET
Logic Output.
RESET goes low whenever V
CC
falls below the reset voltage threshold (4.65 V
typ).
RESET remains low for a minimum of
140 ms after V
CC
returns to 5 V.
RESET also
goes low for a minimum of 140 ms if the watchdog
timer is enabled but not serviced within its time-
out period.
WDI
Watchdog Input. WDI is a three level input. If
WDI remains either high or low for longer than
the watchdog timeout period,
RESET pulses low
and
WDO goes low. The timer resets with each
transition on the WDI line. The watchdog timer
may be disabled if WDI is left floating or is driven
to midsupply.
RESET
(SOIC packages only) Logic Output. RESET is
an active high output. It is the inverse of
RESET.
WDO
(SOIC ADM8699 only) Logic Output. The
Watchdog Output,
WDO, goes low if WDI
remains either high or low for longer than the
watchdog timeout period.
WDO is set high by the
next transition at WDI. If WDI is unconnected or
at midsupply, the watchdog timer is disabled and
WDO remains high.
PIN CONFIGURATIONS
8-Lead DIP & SOIC
1
2
3
4
8
7
6
5
TOP VIEW
(Not to Scale)
O
TOP VIEW
(Not to Scale)
ADM8698/
ADM8699
V
CC
V
CC
GND
GND
GND
NC (WDI)
*
NC
*
( ) ADM8699 ONLY
RESET
NC = NO CONNECT
16-Lead SOIC
1
2
3
4
16
15
14
13
TOP VIEW
(Not to Scale)
O
5
12
6
11
7
10
8
9
TOP VIEW
(Not to Scale)
ADM8698/
ADM8699
GND
V
CC
V
CC
GND
NC
NC
NC
NC
RESET
NC
NC
NC (WDI)
*
NC
GND
RESET
NC (WDO)
*
*( ) ADM8699 ONLY
NC = NO CONNECT
TYPICAL PERFORMANCE CURVES
10
90
100
0%
1V
A4
500ms
3.36 V
1V
Figure 1. RESET Output Voltage vs. V
CC
TEMPERATURE
C
50
90
30
10
10
30
50
70
230
170
RESET DELAY ms
200
220
210
190
180
Figure 2. RESET Timeout Delay vs. Temperature
TEMPERATURE
C
60
30
0
30
60
90
120
4.69
4.57
RESET VOLTAGE THRESHOLD V
4.63
4.67
4.65
4.61
4.59
4.55
Figure 3. RESET Voltage Threshold vs. Temperature
ADM8698/ADM8699
REV. 0
4
C2926102/97
PRINTED IN U.S.A.
CIRCUIT INFORMATION
Power Fail RESET
A precision voltage detector monitors V
CC
and generates a
RESET output to hold the microprocessor's Reset line low when
V
CC
falls below the reset threshold 4.65 V (see Figure 4). The
reset voltage threshold is set to accommodate a 5% variation on
V
CC
. The voltage detector has 40 mV hysteresis to ensure that
glitches on V
CC
do not activate the
RESET output.
On power-up, an internal monostable holds
RESET low for
140 ms after V
CC
rises above the reset threshold. This allows the
power supply to stabilize on power-up and also prevents repeated
toggling of
RESET even if the 5 V power drops out and recovers
with each power line cycle. In order to prevent mistriggering
due to transient voltage spikes, it is recommended that a 0.1
F
capacitor be connected at the V
CC
pin.
The
RESET output is guaranteed to remain low with V
CC,
as
low as 1 V. This holds the microprocessor in a stable shutdown
condition as the power supply comes up.
On the 16-lead SOIC package, an active high RESET output is
also provided. This is the complement of
RESET and is in-
tended for microprocessors requiring an active high signal.
V
2
V
2
V
1
V
1
V
CC
RESET
V
1
= RESET VOLTAGE THRESHOLD
V
2
= RESET VOLTAGE THRESHOLD +
THRESHOLD HYSTERESIS
t
1
= RESET TIME
t
1
t
1
Figure 4. Watchdog Timeout Period vs. Temperature
Watchdog Timer (ADM8699 Only)
The watchdog timer input (WDI) monitors an I/O line from the
P system. The
P must toggle this input once every 1.6 sec-
onds to verify correct software execution. Failure to toggle the
line indicates that the
P system is not correctly executing its
program and may be tied up in an endless loop. If this happens,
a reset pulse is generated to initialize the processor.
The WDI input is a three level input and will recognize a low-
to-high or high-to-low transition on its input. The watchdog
timer is reset by each WDI transition and then begins its timeout
period. If the WDI pin remains either high or low, reset pulses
will be issued every 1.6 seconds typically. If the watchdog timer
is not needed, the WDI input should be left floating.
The Watchdog Output (
WDO) (SOIC package Only) provides
watchdog status information. It is driven low if WDI is not
toggled within the watchdog timeout period. It goes high at the
next WDI transition. It is also set high when V
CC
falls below the
reset threshold.
t
1 = RESET TIME
t
2 = WATCHDOG TIME OUT PERIOD
t
1
t
1
WDI
RESET
t
1
WDO
t
2
t
2
Figure 5. Watchdog Timeout Period and Reset Active Time
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
8-Pin Plastic DIP (N-8)
8-Pin SOIC (R-8)
16-Lead SOIC (R-16)
PIN 1
SEATING
PLANE
0.430 (10.92)
MAX
1
4
5
8
0.018 (0.46)
0.033 (0.84)
0.1 (2.54)
BSC
0.125
(3.18)
MIN
0.035
(0.89)
0.18 (4.57)
0.25
(6.35)
0.31
(7.87)
0.011
(0.28)
0.18
(4.57)
MAX
0.3 (7.62)
8
5
4
1
0.1968 (5.00)
0.1890 (4.80)
0.1574 (4.00)
0.1497 (3.80)
0.2440 (6.20)
0.2284 (5.80)
PIN 1
SEATING
PLANE
0.0098 (0.25)
0.0040 (0.10)
0.0192 (0.49)
0.0138 (0.35)
0.102 (2.59)
0.094 (2.39)
0.0500
(1.27)
BSC
0.0098 (0.25)
0.0075 (0.19)
0.0500 (1.27)
0.0160 (0.41)
8
0
0.0196 (0.50)
0.0099 (0.25)
x 45
0.019 (0.49)
0.05 (1.27)
REF
0.104
(2.65)
0.012
(0.3)
0.413 (10.50)
0.419
(10.65)
0.299
(7.60)
1
8
9
16
0.042
(1.07)
0.013
(0.32)
0.030
(0.75)
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