Preliminary Technical Data
FEATURES
Low Voltage Supervisory Circuits with
Watchdog & Manual Reset in 5-Lead SOT-23
ADM6821–ADM6825
FUNCTIONAL BLOCK DIAGRAM
V
CC
Precision Low Voltage Monitoring down to 1.8V
9 Reset Threshold Options:
1.58V to 4.63V
140ms (Min) Reset Timeout
Watchdog Timer with 1.6s Timeout
Manual Reset Input
Reset Output Stages
Push-Pull Active-Low
Open-Drain Active-Low
Push-Pull Active-High
Low Power Consumption (3µA)
Guaranteed Reset Output valid to V
CC
=1V
Power Supply Glitch Immunity
Specified from -40°C to +125°C
5-Lead SOT-23 Package
ADM6821
V
CC
V
REF
RESET
GENERATOR
RESET
MR
DEBOUNCE
WATCHDOG
DETECTOR
GND
WDI
APPLICATIONS
Microprocessor Systems
Computers
Controllers
Intelligent Instruments
Portable Equipment
GENERAL DESCRIPTION
The ADM6821-ADM6825 are supervisory circuits which
monitor power supply voltage levels and code execution
integrity in microprocessor-based systems. As well as providing
power-on-reset signals, an on-chip watchdog timer can reset the
microprocessor if it fails to strobe within a preset timeout
period. A reset signal can also be asserted by means of an
external push-button, through a manual reset input. The three
parts feature different combinations of watchdog input, manual
reset input and output stage configuration, as shown in table 1.
Each part is available in a choice of 9 reset threshold options
ranging from 1.58V to 4.63V. The reset and watchdog timeout
periods are fixed at 140ms (min) and 1.6s (typ), respectively.
The ADM6821-ADM6825 are available in 5-lead SOT-23
packages and typically consume only 3µA, making them
suitable for use in low power portable applications.
Table 1. Selection Table
Part No.
ADM6821
ADM6822
ADM6823
ADM6824
ADM6825
Watchdog Timer
Yes
Yes
Yes
Yes
-
Manual Reset
Yes
Yes
Yes
-
Yes
Output Stage
RESET
-
Open-Drain
Push-Pull
Push-Pull
Push-Pull
RESET
Push-Pull
-
-
Push-Pull
Push-Pull
Rev. PrA
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 companies.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
www.analog.com
Tel: 781.329.4700
Fax: 781.326.8703
© 2004 Analog Devices, Inc. All rights reserved.
ADM6821–ADM6825
ADM6821–ADM6825—SPECIFICATIONS
Preliminary Technical Data
Table 2. V
CC
=4. 5V to 5.5V for ADM682_L/M, V
CC
=2.7V to 3.6V for ADM682_T/S/R, V
CC
=2.1V to 2.75V for ADM682_Z/Y,
V
CC
=1.53V to 2.0V for ADM682_W/V, T
A
=-40°C to +125°C, unless otherwise noted.
Parameter
SUPPLY
V
CC
Operating Voltage Range
Supply Current (WDI and MR unconnected)
Min
1
1.2
10
Typ
Max
5.5
5.5
24
30
7
16
25
5
12
Units
V
V
µA
µA
µA
µA
µA
Test Conditions/Comments
T
A
=0°C to +70°C
T
A
=--40°C to +125°C
V
CC
=5.5V, no load,
T
A
=--40°C to +85°C
V
CC
=5.5V, no load,
T
A
=--40°C to +125°C
V
CC
=3.6V, no load,
T
A
=--40°C to +85°C
V
CC
=3.6V, no load,
T
A
=--40°C to +125°C
V
CC
=3.6V, no load,
T
A
=--40°C to +85°C
(ADM6825 only)
V
CC
=3.6V, no load,
T
A
=--40°C to +125°C
(ADM6825 only)
T
A
=-40°C to +85°C
T
A
=-40°C to +125°C
T
A
=-40°C to +85°C
T
A
=-40°C to +125°C
T
A
=-40°C to +85°C
T
A
=-40°C to +125°C
T
A
=-40°C to +85°C
T
A
=-40°C to +125°C
T
A
=-40°C to +85°C
T
A
=-40°C to +125°C
T
A
=-40°C to +85°C
T
A
=-40°C to +125°C
T
A
=-40°C to +85°C
T
A
=-40°C to +125°C
T
A
=-40°C to +85°C
T
A
=-40°C to +125°C
T
A
=-40°C to +85°C
20
µA
RESET THRESHOLD VOLTAGE
ADM682_L
ADM682_M
ADM682_T
ADM682_S
ADM682_R
ADM682_Z
ADM682_Y
ADM682_W
ADM682_V
RESET THRESHOLD TEMPERATURE COEFFICIENT
RESET THRESHOLD HYSTERESIS
RESET TIMEOUT PERIOD
V
CC
TO RESET DELAY
RESET Output Voltage Low
4.50
4.47
4.25
4.22
3.00
2.97
2.85
2.83
2.55
2.53
2.25
2.24
2.12
2.11
1.62
1.61
1.52
4.63
4.38
3.08
2.93
2.63
2.32
2.19
1.67
1.58
60
2x V
TH
200
20
4.75
4.78
4.50
4.53
3.15
3.17
3.00
3.02
2.70
2.72
2.38
2.40
2.25
2.27
1.71
1.72
1.62
140
100
280
320
0.4
0.3
0.3
0.3
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
ppm/°C
mV
ms
ms
µs
V
V
V
V
V
RESET Output Voltage High
0.8×V
CC
V
CC
= V
TH
to (V
TH
- 100mV)
V
CC
>=4.25V, I
SINK
=3.2mA, reset
asserted
V
CC
>=2.55V, I
SINK
=1.2mA, reset
asserted
V
CC
>=1.25V, I
SINK
=100uA, reset
asserted
V
CC
>=1.0V, I
SINK
=50uA, reset
asserted, T
A
=-40°C to +85°C
V
CC
>=4.75V, I
SOURCE
=800uA,
reset not asserted
Rev.PrA | Page 2 of 7
Preliminary Technical Data
Parameter
Min
0.8×V
CC
0.8×V
CC
RESET Output Voltage High
0.8×V
CC
0.8×V
CC
0.8×V
CC
0.8×V
CC
RESET Output Voltage Low
0.4
0.3
0.3
WATCHDOG INPUT (ADM6821-ADM6824)
Watchdog Timeout Period
WDI Pulse Width
WDI Input Threshold
V
IL
V
IH
WDI Input Current
MANUAL RESET INPUT (ADM6821-ADM6823/ADM6825)
MR Input Threshold
MR Input Pulse Width
MR Glitch Rejection
MR Pull-up Resistance
MR to Reset Delay
0.7xV
CC
1
25
100
50
200
75
V
V
V
Typ
Max
Units
V
V
ADM6821–ADM6825
Test Conditions/Comments
V
CC
>=3.15V, I
SOURCE
=500uA,
reset not asserted
V
CC
>=1.8V, I
SOURCE
=200uA,
reset not asserted
V
CC
>=4.25V, I
SOURCE
=800uA,
reset asserted
V
CC
>=2.55V, I
SOURCE
=500uA,
reset asserted
V
CC
>=1.50V, I
SOURCE
=100uA,
reset asserted
V
CC
>=1.0V, I
SOURCE
=1uA,
reset asserted, T
A
=-40°C to +85°C
V
CC
>=4.75V, I
SINK
=3.2mA,
reset not asserted
V
CC
>=3.15V, I
SINK
=1.2mA,
reset not asserted
V
CC
>=1.8V, I
SINK
=500uA,
reset not asserted
1.12
50
1.6
2.40
s
ns
V
V
µA
µA
V
V
µs
ns
k
ns
V
IL
=0.4V, V
IH
=0.8×V
CC
,
0.3xV
CC
0.7xV
CC
-20
120
-15
160
V
WDI
= V
CC
, time average
V
WDI
=0, time average
0.3xV
CC
ABSOLUTE MAXIMUM RATINGS
Table 3. T
A
= 25°C unless otherwise noted.
Parameter
V
CC
Output Current (RESET, RESET)
Operating Temperature Range
Storage Temperature Range
θ
JA
Thermal Impedance
Lead Temperature
Soldering (10 sec)
Vapour Phase (60 sec)
Infrared (15 sec)
Rating
-0.3V to +6V
20mA
-40°C to +125°C
-65°C to +150°C
270°C/W
300°C
215°C
220°C
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 indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
Rev.PrA | Page 3 of 7
ADM6821–ADM6825
PIN CONFIGURATIONS AND FUNCTIONAL DESCRIPTIONS
RESET 1
GND
MR
2
3
ADM6821
(Not to Scale)
Preliminary Technical Data
5
V
CC
RESET
GND
1
2
3
ADM6822/
ADM6823
(Not to Scale)
5
V
CC
TOP VIEW
TOP VIEW
4 WDI
MR
4 WDI
RESET
GND
RESET
1
ADM6824
5
TOP VIEW
V
CC
RESET
GND
1
ADM6825
5
TOP VIEW
V
CC
2
3
2
3
(Not to Scale)
(Not to Scale)
4 WDI
RESET
4
MR
Table 4. Pin Functional Descriptions
Pin No.
1
Name
RESET (ADM6822/23/24/25)
2
3
RESET (ADM6821)
GND
MR (ADM6821/22/23)
4
RESET (ADM6824/ADM6825)
WDI (ADM6821/22/23/24)
MR (ADM6825)
5
V
CC
Description
Active-Low Reset Output, which is asserted whenever V
CC
is below the reset.threshold,
V
TH
.
Open-Drain Output Stage for ADM6822.
Push-Pull Output Stage for ADM6823/24/25.
Active-High Reset Output
Ground
Manual Reset Input. This is an active-low input which, when forced low for at least 1µs,
generates a reset.
Features a 52k internal pull-up.
Active-High Push-Pull Reset Output.
Watchdog Input. Generates a reset if the voltage on the pin remains low or high for the
duration of the watchdog timeout. The timer is cleared if a logic transition occurs on this
pin or if a reset is generated.
Manual Reset Input.
Power Supply Voltage being Monitored
ESD 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 this product features
proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy
electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance
degradation or loss of functionality.
`
Rev.PrA | Page 4 of 7
Preliminary Technical Data
ORDERING GUIDE
Model
ADM6821LART-RL
ADM6821LART-RL7
ADM6821MART-RL
ADM6821MART-RL7
ADM6821TART-RL
ADM6821TART-RL7
ADM6821SART-RL
ADM6821SART-RL7
ADM6821RART-RL
ADM6821RART-RL7
ADM6821ZART-RL
ADM6821ZART-RL7
ADM6821YART-RL
ADM6821YART-RL7
ADM6821WART-RL
ADM6821WART-RL7
ADM6821VART-RL
ADM6821VART-RL7
ADM6822LART-RL
ADM6822LART-RL7
ADM6822MART-RL
ADM6822MART-RL7
ADM6822TART-RL
ADM6822TART-RL7
ADM6822SART-RL
ADM6822SART-RL7
ADM6822RART-RL
ADM6822RART-RL7
ADM6822ZART-RL
ADM6822ZART-RL7
ADM6822YART-RL
ADM6822YART-RL7
ADM6822WART-RL
ADM6822WART-RL7
ADM6822VART-RL
ADM6822VART-RL7
ADM6823LART-RL
ADM6823LART-RL7
ADM6823MART-RL
ADM6823MART-RL7
ADM6823TART-RL
ADM6823TART-RL7
ADM6823SART-RL
ADM6823SART-RL7
ADM6823RART-RL
ADM6823RART-RL7
ADM6823ZART-RL
ADM6823ZART-RL7
ADM6823YART-RL
ADM6823YART-RL7
Reset Threshold (V)
4.63
4.63
4.38
4.38
3.08
3.08
2.93
2.93
2.63
2.63
2.32
2.32
2.19
2.19
1.67
1.67
1.58
1.58
4.63
4.63
4.38
4.38
3.08
3.08
2.93
2.93
2.63
2.63
2.32
2.32
2.19
2.19
1.67
1.67
1.58
1.58
4.63
4.63
4.38
4.38
3.08
3.08
2.93
2.93
2.63
2.63
2.32
2.32
2.19
2.19
Temperature Range
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
Quantity
10k
3k
10k
3k
10k
3k
10k
3k
10k
3k
10k
3k
10k
3k
10k
3k
10k
3k
10k
3k
10k
3k
10k
3k
10k
3k
10k
3k
10k
3k
10k
3k
10k
3k
10k
3k
10k
3k
10k
3k
10k
3k
10k
3k
10k
3k
10k
3k
10k
3k
ADM6821–ADM6825
Package Type
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
Branding
N0A
N0A
N0A
N0A
N0A
N0A
N0A
N0A
N0A
N0A
N0A
N0A
N0A
N0A
N0A
N0A
N0A
N0A
N0B
N0B
N0B
N0B
N0B
N0B
N0B
N0B
N0B
N0B
N0B
N0B
N0B
N0B
N0B
N0B
N0B
N0B
N0C
N0C
N0C
N0C
N0C
N0C
N0C
N0C
N0C
N0C
N0C
N0C
N0C
N0C
Rev. PrA | Page 5 of 7
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