Supervisory Circuits with Watchdog
and Manual Reset in 5-Lead SC70 & SOT-23
Preliminary Technical Data
ADM823–ADM825
Rev. PrA
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FEATURES
Precision 2.5V to 5V Power Supply Monitor
7 Reset Threshold Options:
2.19V to 4.63V
140ms (Min) Reset Timeout
Watchdog Timer with 1.6s Timeout (ADM823, ADM824)
Manual Reset Input (ADM823, ADM825)
Push-Pull Output Stages
RESET (ADM823)
RESET, RESET (ADM824/ADM825)
Low Power Consumption (3µA)
Guaranteed Reset Output valid to VCC=1V
Power Supply Glitch Immunity
Specified Over Industrial Temperature Range
5-Lead SC70 and SOT-23 Packages
APPLICATIONS
Microprocessor Systems
Computers
Controllers
Intelligent Instruments
Portable Equipment
GENERAL DESCRIPTION
The ADM823-ADM825 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.
FUNCTIONAL BLOCK DIAGRAM
RESET
GENERATOR
MR
DEBOUNCE
GND
RESET
V
CC
V
REF
V
CC
ADM823
WATCHDOG
DETECTOR
WDI
Each part is available in a choice of 7 reset threshold options
ranging from 2.19V to 4.63V. The reset and watchdog timeout
periods are fixed at 140ms (min) and 1.6s (typ), respectively.
The ADM823-ADM825 are available in 5-lead SC70 and
SOT-23 packages and typically consume only 3µA, making
them suitable for use in low power portable applications.
Table 1. Selection Table
Output Stage
Part No. Watchdog Timer Manual Reset RESET RESET
ADM823 Yes Yes Push-Pull -
ADM824 Yes - Push-Pull Push-Pull
ADM825 - Yes Push-Pull Push-Pull
ADM823–ADM825 Preliminary Technical Data
Rev.PrA | Page 2 of 7
ADM823-ADM825—SPECIFICATIONS
Table 2. VCC=4.75V to 5.5V for ADM82_L, VCC=4.5V to 5.5V for ADM82_M, VCC=3.15V to 3.6V for ADM82_T, VCC=3V to 3.6V for
ADM82_S, VCC=2.7V to 3.6V for ADM82_R, VCC=2.38V to 2.75V for ADM82_Z, VCC=2.25V to 2.75V for ADM82_Y, TA=TMIN to
TMAX, unless otherwise noted
Parameter Min Typ Max Units Test Conditions/Comments
SUPPLY
VCC Operating Voltage Range 1 5.5 V TA=0°C to +70°C
1.2 V TA=TMIN to TMAX
Supply Current (SOT-23 only) 10 24 µA WDI and MR unconnected
ADM823L/M, ADM824L/M
5 12 µA
WDI and MR unconnected
ADM823T/S/R/Z/Y,
ADM824T/S/R/Z/Y
4.5 12 µA
MR unconnected
ADM825L/M
3 8 µA
MR unconnected
ADM825T/S/R/Z/Y
Supply Current (SC70 only) 6 17 µA WDI and MR unconnected
ADM823L/M, ADM824L/M
4 12 µA
WDI and MR unconnected
ADM823T/S/R/Z/Y,
ADM824T/S/R/Z/Y
3 8 µA
MR unconnected
ADM825L/M
2 6 µA
MR unconnected
ADM825T/S/R/Z/Y
RESET THRESHOLD VOLTAGE
ADM82_L 4.56 4.63 4.70 V TA=+25°C
4.50 4.75 V TA=TMIN to TMAX
ADM82_M 4.31 4.38 4.45 V TA=+25°C
4.25 4.50 V TA=TMIN to TMAX
ADM82_T 3.04 3.08 3.11 V TA=+25°C
3.00 3.15 V TA=TMIN to TMAX
ADM82_S 2.89 2.93 2.96 V TA=+25°C
2.85 3.00 V TA=TMIN to TMAX
ADM82_R 2.59 2.63 2.66 V TA=+25°C
2.55 2.70 V TA=TMIN to TMAX
ADM82_Z (SC70 only) 2.28 2.32 2.35 V TA=+25°C
2.25 2.38 V TA=TMIN to TMAX
ADM82_Y (SC70 only) 2.16 2.19 2.22 V TA=+25°C
2.13 2.25 V TA=TMIN to TMAX
RESET THRESHOLD TEMPERATURE COEFFICIENT 40 ppm/°C
RESET THRESHOLD HYSTERESIS 10 mV ADM82_L/M
5 mV ADM82_T/S/R/Z/Y
RESET TIMEOUT PERIOD 140 200 280 ms
VCC TO RESET DELAY 40 µs VTH-VCC=100mV
RESET Output Voltage 0.4 V
VCC=VTH min, ISINK=3.2mA,
ADM82_L/M
0.3 V
VCC=VTH min, ISINK=1.2mA,
ADM82_T/S/R/Z/Y
0.3 V
TA=0°C to +70°C, VCC=1V,
VCC falling, ISINK=50µA
V
CC-1.5 V
VCC=VTH max, ISOURCE=120µA,
ADM82_L/M
Preliminary Technical Data ADM823–ADM825
Rev.PrA | Page 3 of 7
Parameter Min Typ Max Units Test Conditions/Comments
0.8×VCC V
VCC=VTH max, ISOURCE=30µA,
ADM82_T/S/R/Z/Y
RESET Output Short Circuit Current 800 µA
RESET=0V, VCC=5.5V,
ADM82_L/M
400 µA
RESET=0V, VCC=5.5V,
ADM82_T/S/R/Z/Y
RESET Output Voltage 0.4 V VCC=VTH max, ISINK=3.2mA,
ADM824L/M, ADM825L/M
0.3 V
VCC=VTH max, ISINK=1.2mA,
ADM824T/S/R/Z/Y,
ADM825T/S/R/Z/Y
0.8×VCC V VCC>=1.8V, ISOURCE=150µA
WATCHDOG INPUT (ADM823, ADM824)
Watchdog Timeout Period 1.12 1.6 2.40 s
WDI Pulse Width 50 ns VIL=0.4V, VIH=0.8×VCC,
WDI Input Threshold
VIL 0.3xVCC V
VIH 0.7xVCC V
WDI Input Current 120 160 µA VWDI= VCC, time average
-20 -15 µA VWDI=0, time average
MANUAL RESET INPUT (ADM823, ADM825)
MR Input Threshold 0.3xVCC V
0.7xVCC V
MR Input Pulse Width 1 µs
MR Glitch Rejection 100 ns
MR Pull-up Resistance 35 52 75 k⍀
MR to Reset Delay 500 ns
ABSOLUTE MAXIMUM RATINGS
Table 3. TA = 25°C unless otherwise noted.
Parameter Rating
VCC -0.3V to +6V
Output Current (RESET, RESET) 20mA
Operating Temperature Range
SC70 -40°C to +85°C
SOT-23 -40°C to +125°C
Storage Temperature Range -65°C to +150°C
θJA Thermal Impedance
SC70 146°C/W
SOT-23 270°C/W
Lead Temperature
Soldering (10 sec) 300°C
Vapour Phase (60 sec) 215°C
Infrared (15 sec) 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.
ADM823–ADM825 Preliminary Technical Data
Rev.PrA | Page 4 of 7
PIN CONFIGURATIONS AND FUNCTIONAL DESCRIPTIONS
1
2
34
5
ADM823
TOP VIEW
(Not to Scale)
V
CC
RESET
GND
MR WDI
1
2
34
5
ADM824
TOP VIEW
(Not to Scale)
V
CC
RESET
GND
RESET WDI
1
2
34
5
ADM825
TOP VIEW
(Not to Scale)
V
CC
RESET
GND
RESET MR
Table 4. Pin Functional Descriptions
Pin No. Name Description
1 RESET Push-Pull Active-Low Reset Output, which is asserted whenever VCC is below the
reset.threshold, VTH.
2 GND Ground
3 MR (ADM823) 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.
RESET (ADM824/ADM825) Active-High, Push-Pull Reset Output.
4 WDI (ADM823/ADM824) 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.
MR (ADM825) Manual Reset Input.
5 VCC 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.
Preliminary Technical Data ADM823–ADM825
Rev. PrA | Page 5 of 7
ORDERING GUIDE (ADM823, ADM824)
Model Reset Threshold (V) Temperature Range Quantity Package Type Branding
ADM823LAKS-RL 4.63 -40°C to +85°C 10k SC70-5 N07
ADM823LAKS-R7 4.63 -40°C to +85°C 3k SC70-5 N07
ADM823LART-RL 4.63 -40°C to +125°C 10k SOT-23-5 N07
ADM823LART-R7 4.63 -40°C to +125°C 3k SOT-23-5 N07
ADM823MAKS-RL 4.38 -40°C to +85°C 10k SC70-5 N07
ADM823MAKS-R7 4.38 -40°C to +85°C 3k SC70-5 N07
ADM823MART-RL 4.38 -40°C to +125°C 10k SOT-23-5 N07
ADM823MART-R7 4.38 -40°C to +125°C 3k SOT-23-5 N07
ADM823TAKS-RL 3.08 -40°C to +85°C 10k SC70-5 N07
ADM823TAKS-R7 3.08 -40°C to +85°C 3k SC70-5 N07
ADM823TART-RL 3.08 -40°C to +125°C 10k SOT-23-5 N07
ADM823TART-R7 3.08 -40°C to +125°C 3k SOT-23-5 N07
ADM823SAKS-RL 2.93 -40°C to +85°C 10k SC70-5 N07
ADM823SAKS-R7 2.93 -40°C to +85°C 3k SC70-5 N07
ADM823SART-RL 2.93 -40°C to +125°C 10k SOT-23-5 N07
ADM823SART-R7 2.93 -40°C to +125°C 3k SOT-23-5 N07
ADM823RAKS-RL 2.63 -40°C to +85°C 10k SC70-5 N07
ADM823RAKS-R7 2.63 -40°C to +85°C 3k SC70-5 N07
ADM823RART-RL 2.63 -40°C to +125°C 10k SOT-23-5 N07
ADM823RART-R7 2.63 -40°C to +125°C 3k SOT-23-5 N07
ADM823ZAKS-RL 2.32 -40°C to +85°C 10k SC70-5 N07
ADM823ZAKS-R7 2.32 -40°C to +85°C 3k SC70-5 N07
ADM823YAKS-RL 2.19 -40°C to +85°C 10k SC70-5 N07
ADM823YAKS-R7 2.19 -40°C to +85°C 3k SC70-5 N07
ADM824LAKS-RL 4.63 -40°C to +85°C 10k SC70-5 N08
ADM824LAKS-R7 4.63 -40°C to +85°C 3k SC70-5 N08
ADM824LART-RL 4.63 -40°C to +125°C 10k SOT-23-5 N08
ADM824LART-R7 4.63 -40°C to +125°C 3k SOT-23-5 N08
ADM824MAKS-RL 4.38 -40°C to +85°C 10k SC70-5 N08
ADM824MAKS-R7 4.38 -40°C to +85°C 3k SC70-5 N08
ADM824MART-RL 4.38 -40°C to +125°C 10k SOT-23-5 N08
ADM824MART-R7 4.38 -40°C to +125°C 3k SOT-23-5 N08
ADM824TAKS-RL 3.08 -40°C to +85°C 10k SC70-5 N08
ADM824TAKS-R7 3.08 -40°C to +85°C 3k SC70-5 N08
ADM824TART-RL 3.08 -40°C to +125°C 10k SOT-23-5 N08
ADM824TART-R7 3.08 -40°C to +125°C 3k SOT-23-5 N08
ADM824SAKS-RL 2.93 -40°C to +85°C 10k SC70-5 N08
ADM824SAKS-R7 2.93 -40°C to +85°C 3k SC70-5 N08
ADM824SART-RL 2.93 -40°C to +125°C 10k SOT-23-5 N08
ADM824SART-R7 2.93 -40°C to +125°C 3k SOT-23-5 N08
ADM824RAKS-RL 2.63 -40°C to +85°C 10k SC70-5 N08
ADM824RAKS-R7 2.63 -40°C to +85°C 3k SC70-5 N08
ADM824RART-RL 2.63 -40°C to +125°C 10k SOT-23-5 N08
ADM824RART-R7 2.63 -40°C to +125°C 3k SOT-23-5 N08
ADM824ZAKS-RL 2.32 -40°C to +85°C 10k SC70-5 N08
ADM824ZAKS-R7 2.32 -40°C to +85°C 3k SC70-5 N08
ADM824YAKS-RL 2.19 -40°C to +85°C 10k SC70-5 N08
ADM824YAKS-R7 2.19 -40°C to +85°C 3k SC70-5 N08
ADM823–ADM825 Preliminary Technical Data
Rev.PrA | Page 6 of 7
ORDERING GUIDE (ADM825)
Model Reset Threshold (V) Temperature Range Quantity Package Type Branding
ADM825LAKS-RL 4.63 -40°C to +85°C 10k SC70-5 N09
ADM825LAKS-R7 4.63 -40°C to +85°C 3k SC70-5 N09
ADM825LART-RL 4.63 -40°C to +125°C 10k SOT-23-5 N09
ADM825LART-R7 4.63 -40°C to +125°C 3k SOT-23-5 N09
ADM825MAKS-RL 4.38 -40°C to +85°C 10k SC70-5 N09
ADM825MAKS-R7 4.38 -40°C to +85°C 3k SC70-5 N09
ADM825MART-RL 4.38 -40°C to +125°C 10k SOT-23-5 N09
ADM825MART-R7 4.38 -40°C to +125°C 3k SOT-23-5 N09
ADM825TAKS-RL 3.08 -40°C to +85°C 10k SC70-5 N09
ADM825TAKS-R7 3.08 -40°C to +85°C 3k SC70-5 N09
ADM825TART-RL 3.08 -40°C to +125°C 10k SOT-23-5 N09
ADM825TART-R7 3.08 -40°C to +125°C 3k SOT-23-5 N09
ADM825SAKS-RL 2.93 -40°C to +85°C 10k SC70-5 N09
ADM825SAKS-R7 2.93 -40°C to +85°C 3k SC70-5 N09
ADM825SART-RL 2.93 -40°C to +125°C 10k SOT-23-5 N09
ADM825SART-R7 2.93 -40°C to +125°C 3k SOT-23-5 N09
ADM825RAKS-RL 2.63 -40°C to +85°C 10k SC70-5 N09
ADM825RAKS-R7 2.63 -40°C to +85°C 3k SC70-5 N09
ADM825RART-RL 2.63 -40°C to +125°C 10k SOT-23-5 N09
ADM825RART-R7 2.63 -40°C to +125°C 3k SOT-23-5 N09
ADM825ZAKS-RL 2.32 -40°C to +85°C 10k SC70-5 N09
ADM825ZAKS-R7 2.32 -40°C to +85°C 3k SC70-5 N09
ADM825YAKS-RL 2.19 -40°C to +85°C 10k SC70-5 N09
ADM825YAKS-R7 2.19 -40°C to +85°C 3k SC70-5 N09
Preliminary Technical Data ADM823–ADM825
Rev. PrA | Page 7 of 7
OUTLINE DIMENSIONS
0.087 (2.20)
0.071 (1.80)
PIN 1
0.094 (2.40)
0.071 (1.80)
0.051 (1.30)
BSC
0.026 (0.65) BSC
1 3
4
2
0.053 (1.35)
0.045 (1.15)
0.004 (0.10) 0.004 (0.10)
o
8
0.012 (0.30)
0.006 (0.15)
0.004 (0.10)
0.000 (0.00)
0.039 (1.00)
0.031 (0.80)
SEATING
PLANE
0.043 (1.10)
0.031 (0.80)
0.007 (0.18) 0.012 (0.30)
0
o
5
Figure 1. 5-Lead Plastic Surface Mount Package [SC-70]
(KS-5)
Dimensions shown in millimeters
PIN 1
1.60 BSC 2.80 BSC
1.90
BSC
0.95 BSC
1 3
4 5
2
0.22
0.08
10
5
0
0.50
0.3
0.15 MAX SEATING
PLANE
1.45 MAX
1.30
1.15
0.90
2.90 BSC
0.$
0.45
0.3
COMPLIANT TO JEDEC STANDARDS MO-178AA
Figure 1. 5-Lead Small Outline Transistor Package [SOT-23]
(RT-5)
Dimensions shown in millimeters
© 2004 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective companies.
Printed in the U.S.A.
PR04534-0-2/04(PrA)
