Data Sheet
FEATURES
Supervisory Circuits with Watchdog and
Manual Reset in 5-Lead SC70 and SOT-23
ADM823/ADM824/ADM825
FUNCTIONAL BLOCK DIAGRAM
ADM823
V
CC
V
CC
V
REF
RESET
GENERATOR
Precision 2.5 V to 5 V power supply monitor
7 reset threshold options: 2.19 V to 4.63 V
140 ms (minimum) reset timeout
Watchdog timer with 1.6 sec timeout (ADM823, ADM824)
Manual reset input (ADM823, ADM825)
Push-pull output stages
RESET (ADM823)
RESET, RESET (ADM824/ADM825)
Low power consumption: 5 µA
Guaranteed reset output valid to V
CC
= 1 V
Power supply glitch immunity
Specified over automotive temperature range
5-lead SC70 and SOT-23 packages
RESET
MR
DEBOUNCE
WATCHDOG
DETECTOR
04534-001
GND
WDI
Figure 1.
APPLICATIONS
Microprocessor systems
Computers
Controllers
Intelligent instruments
Portable equipment
GENERAL DESCRIPTION
The ADM823/ADM824/ADM825 are supervisory circuits that
monitor power supply voltage levels and code execution integrity
in microprocessor-based systems. In addition to 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 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.
Table 1. Selection Table
Output Stage
Part No.
ADM823
ADM824
ADM825
Watchdog Timer
Yes
Yes
–
Manual Reset
Yes
–
Yes
RESET
Push-Pull
Push-Pull
Push-Pull
RESET
–
Push-Pull
Push-Pull
These parts are available in a choice of seven reset threshold
options ranging from 2.19 V to 4.63 V. The reset and watchdog
timeout periods are fixed at 140 ms (minimum) and 1.6 sec
(typical), respectively.
The ADM823/ADM824/ADM825 are available in 5-lead SC70
and SOT-23 packages and typically consume only 5 µA, making
them suitable for use in low power, portable applications.
Rev. D
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ADM823/ADM824/ADM825
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Functional Block Diagram .............................................................. 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings ............................................................ 5
ESD Caution .................................................................................. 5
Pin Configurations and Function Descriptions ........................... 6
Typical Performance Characteristics ............................................. 7
Circuit Description ........................................................................... 9
Data Sheet
Reset Output ..................................................................................9
Manual Reset Input .......................................................................9
Watchdog Input .............................................................................9
Applications Information .............................................................. 10
Watchdog Input Current ........................................................... 10
Negative-Going V
CC
Transients ................................................ 10
Ensuring Reset Valid to V
CC
= 0 V ........................................... 10
Watchdog Software Considerations ......................................... 10
Outline Dimensions ....................................................................... 11
Ordering Guide .......................................................................... 11
REVISION HISTORY
7/13—Rev. C to Rev. D
Change to Figure 16 .......................................................................... 9
Updated Outline Dimensions ........................................................11
10/10—Rev. B to Rev. C
Updated Outline Dimensions ....................................................... 11
Changes to Ordering Guide .......................................................... 11
5/08—Rev. A to Rev. B
Changes to General Description Section ...................................... 1
Changes to Table 4 ............................................................................ 6
Changes to Ordering Guide .......................................................... 11
2/07—Rev. 0 to Rev. A
Updated Format .................................................................. Universal
Changes to Ordering Guide .......................................................... 11
10/04—Revision 0: Initial Version
Rev. D | Page 2 of 12
Data Sheet
SPECIFICATIONS
ADM823/ADM824/ADM825
V
CC
= 4.75 V to 5.5 V for ADM82xL, V
CC
= 4.5 V to 5.5 V for ADM82xM, V
CC
= 3.15 V to 3.6 V for ADM82xT, V
CC
= 3 V to 3.6 V
for ADM82xS, V
CC
= 2.7 V to 3.6 V for ADM82xR, V
CC
= 2.38 V to 2.75 V for ADM82xZ, V
CC
= 2.25 V to 2.75 V for ADM82xY,
T
A
= T
MIN
to T
MAX
, unless otherwise noted.
Table 2.
Parameter
SUPPLY
V
CC
Operating Voltage Range
Supply Current
Min
1
1.2
10
5
RESET THRESHOLD VOLTAGE
ADM82xL
ADM82xM
ADM82xT
ADM82xS
ADM82xR
ADM82xZ (SC70 Only)
ADM82xY (SC70 Only)
RESET THRESHOLD TEMPERATURE COEFFICIENT
RESET THRESHOLD HYSTERESIS
RESET TIMEOUT PERIOD
V
CC
TO RESET DELAY
RESET/RESET
RESET Output Voltage
140
Typ
Max
5.5
24
12
Unit
V
V
µA
µA
Test Conditions/Comments
T
A
= 0°C to 70°C
T
A
= T
MIN
to T
MAX
WDI and MR unconnected
ADM82xL/M
WDI and MR unconnected
ADM82xT/S/R/Z/Y
T
A
= 25°C
T
A
= T
MIN
to T
MAX
T
A
= 25°C
T
A
= T
MIN
to T
MAX
T
A
= 25°C
T
A
= T
MIN
to T
MAX
T
A
= 25°C
T
A
= T
MIN
to T
MAX
T
A
= 25°C
T
A
= T
MIN
to T
MAX
T
A
= 25°C
T
A
= T
MIN
to T
MAX
T
A
= 25°C
T
A
= T
MIN
to T
MAX
ADM82xL/M
ADM82xT/S/R/Z/Y
V
TH
− V
CC
= 100 mV
V
CC
= V
TH
min, I
SINK
= 3.2 mA,
ADM82xL/M
V
CC
= V
TH
min, I
SINK
= 1.2 mA,
ADM82xT/S/R/Z/Y
T
A
= 0°C to 70°C, V
CC
= 1 V,
V
CC
falling, I
SINK
= 50 µA
V
CC
= V
TH
max, I
SOURCE
= 120 µA,
ADM82xL/M
V
CC
= V
TH
max, I
SOURCE
= 30 µA,
ADM82xT/S/R/Z/Y
V
CC
= V
TH
max, I
SINK
= 3.2 mA,
ADM82xL/M
V
CC
= V
TH
max, I
SINK
= 1.2 mA,
ADM82xT/S/R/Z/Y
V
CC
≥ 1.8 V, I
SOURCE
= 150 µA
4.56
4.50
4.31
4.25
3.04
3.00
2.89
2.85
2.59
2.55
2.28
2.25
2.16
2.13
4.63
4.38
3.08
2.93
2.63
2.32
2.19
40
10
5
200
40
4.70
4.75
4.45
4.50
3.11
3.15
2.96
3.00
2.66
2.70
2.35
2.38
2.22
2.25
280
V
V
V
V
V
V
V
V
V
V
V
V
V
V
ppm/°C
mV
mV
ms
µs
V
V
V
V
V
0.4
0.3
0.3
V
CC
− 1.5
0.8 × V
CC
RESET Output Voltage (ADM824, ADM825)
0.4
0.3
0.8 × V
CC
V
V
V
Rev. D | Page 3 of 12
ADM823/ADM824/ADM825
Parameter
WATCHDOG INPUT (ADM823, ADM824)
Watchdog Timeout Period
WDI Pulse Width
WDI Input Threshold, V
IL
WDI Input Current
MANUAL RESET INPUT (ADM823, ADM825)
MR Input Threshold
MR Input Pulse Width
MR Glitch Rejection
MR Pull-Up Resistance
MR to Reset Delay
Min
1.12
50
0.7 × V
CC
−20
0.7 × V
CC
1
35
100
52
500
Typ
1.6
Max
2.40
0.3 × V
CC
160
Unit
sec
ns
V
µA
µA
V
µs
ns
kΩ
ns
Data Sheet
Test Conditions/Comments
V
IL
= 0.4 V, V
IH
= 0.8 × V
CC
V
WDI
= V
CC
, time average
V
WDI
= 0 V, time average
120
−15
0.3 × V
CC
75
Rev. D | Page 4 of 12
Data Sheet
ABSOLUTE MAXIMUM RATINGS
T
A
= 25°C, unless otherwise noted.
Table 3.
Parameter
V
CC
Output Current (RESET, RESET)
All Other Pins
Operating Temperature Range
Storage Temperature Range
θ
JA
Thermal Impedance
SC70
SOT-23
Lead Temperature
Soldering (10 sec)
Vapor Phase (60 sec)
Infrared (15 sec)
Rating
−0.3 V to +6 V
20 mA
−0.3 V to (V
CC
+ 0.3 V)
−40°C to +125°C
−65°C to +150°C
146°C/W
270°C/W
300°C
215°C
220°C
ADM823/ADM824/ADM825
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.
ESD CAUTION
Rev. D | Page 5 of 12
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