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Low Voltage Supervisory Circuits with
Watchdog and Manual Reset in 5-Lead SOT-23
Data Sheet
FEATURES
Precision low voltage monitoring
9 reset threshold options: 1.58 V to 4.63 V
140 ms (minimum) reset timeout
Watchdog timer with 1.6 sec timeout
Manual reset input
Reset output stages
Push-pull active-low
Open-drain active-low
Push-pull active-high
Low power consumption: 7 µA
Guaranteed reset output valid to V
CC
= 1 V
Power supply glitch immunity
Specified from
−40°C
to +125°C
5-lead SOT-23 package
ADM6823/ADM6824/ADM6825
FUNCTIONAL BLOCK DIAGRAM
ADM6823
V
CC
V
CC
V
REF
RESET
GENERATOR
RESET
MR
DEBOUNCE
WATCHDOG
DETECTOR
04535-001
GND
WDI
Figure 1.
APPLICATIONS
Microprocessor systems
Computers
Controllers
Intelligent instruments
Portable equipment
GENERAL DESCRIPTION
The
ADM6823/ADM6824/ADM6825
are supervisory circuits
that 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 parts
feature different combinations of watchdog input and manual
reset input and output stage configurations, as shown in Table 1.
Each part is available in nine reset threshold options, ranging
from 1.58 V to 4.63 V. The reset and watchdog timeout periods
are fixed at 140 ms (minimum) and 1.6 sec (typical),
respectively.
The
ADM6823/ADM6824/ADM6825
are available in 5-lead
SOT-23 packages and typically consume only 7 µA, making
them suitable for use in low power, portable applications.
Table 1. Selection Table
Part No.
ADM6823
ADM6824
ADM6825
Watchdog
Timer
Yes
Yes
Yes
Manual
Reset
Yes
Output Stage
RESET
Push-Pull
Push-Pull
Push-Pull
Push-Pull
Push-Pull
RESET
Rev. B
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ADM6823/ADM6824/ADM6825
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 Configuration and Function Descriptions ............................. 6
Typical Performance Characteristics ............................................. 7
Theory of Operation ........................................................................ 9
Data Sheet
Reset Output ..................................................................................9
Manual Reset Input .......................................................................9
Watchdog Input .............................................................................9
Application 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 .......................................................................... 12
REVISION HISTORY
2/13—Rev. A to Rev. B
Updated Outline Dimensions ...................................................... 11
Changes to Ordering Guide .......................................................... 12
Deleted Automotive Products Section......................................... 12
9/12—Rev. 0 to Rev. A
Removed ADM6821/ADM6822 (Throughout) ........................... 1
Updated Outline Dimensions ....................................................... 11
Changes to Ordering Guide .......................................................... 11
Added Automotive Products Section........................................... 11
6/05—Revision 0: Initial Version
Rev. B | Page 2 of 12
Data Sheet
SPECIFICATIONS
ADM6823/ADM6824/ADM6825
V
CC
= 4.5 V to 5.5 V for ADM682xL/ADM682xM; V
CC
= 2.7 V to 3.6 V for ADM682xT/ADM682xS/ADM682xR; V
CC
= 2.1 V to 2.75 V
for ADM682xZ/ADM682xY; V
CC
= 1.53 V to 2.0 V for ADM682xW/ADM682xV; T
A
= –40°C to +125°C, unless otherwise noted.
Table 2.
Parameter
SUPPLY
V
CC
Operating Voltage Range
Supply Current
RESET THRESHOLD VOLTAGE
ADM682xL
ADM682xM
ADM682xT
ADM682xS
ADM682xR
ADM682xZ
ADM682xY
ADM682xW
ADM682xV
RESET THRESHOLD TEMPERATURE COEFFICIENT
RESET THRESHOLD HYSTERESIS
V
CC
TO RESET DELAY
RESET TIMEOUT PERIOD
RESET OUTPUT VOLTAGE
V
OL
(Push-Pull or Open-Drain)
Min
1
10
7
4.50
4.25
3.00
2.85
2.55
2.25
2.12
1.62
1.52
4.63
4.38
3.08
2.93
2.63
2.32
2.19
1.67
1.58
60
2 × V
TH
20
200
Typ
Max
5.5
20
16
4.75
4.50
3.15
3.00
2.70
2.38
2.25
1.71
1.62
Unit
V
µA
µA
V
V
V
V
V
V
V
V
V
ppm/°C
mV
µs
ms
V
V
V
V
V
V
V
µA
V
CC
≥ 1 V, I
SINK
= 50 µA
V
CC
≥ 1.2 V, I
SINK
= 100 µA
V
CC
≥ 2.55 V, I
SINK
= 1.2 mA
V
CC
≥ 4.25 V, I
SINK
= 3.2 mA
V
CC
≥ 1.8 V, I
SOURCE
= 200 µA
V
CC
≥ 3.15 V, I
SOURCE
= 500 µA
V
CC
≥ 4.75 V, I
SOURCE
= 800 µA
RESET not asserted
Test Conditions/Comments
WDI and MR unconnected, V
CC
= 5.5 V
WDI and MR unconnected, V
CC
= 3.6 V
V
TH
−
V
CC
= 100 mV
140
280
0.3
0.3
0.3
0.4
V
OH
(Push-Pull Only)
0.8 × V
CC
0.8 × V
CC
0.8 × V
CC
1
RESET OUTPUT LEAKAGE CURRENT (OPEN-
DRAIN ONLY)
RESET OUTPUT VOLTAGE (PUSH-PULL ONLY)
V
OH
0.8 × V
CC
0.8 × V
CC
0.8 × V
CC
0.8 × V
CC
0.3
0.3
0.4
V
OL
V
V
V
V
V
V
V
V
CC
≥ 1 V, I
SOURCE
= 1 µA
V
CC
≥ 1.5 V, I
SOURCE
= 100 µA
V
CC
≥ 2.55 V, I
SOURCE
= 500 µA
V
CC
≥ 4.25 V, I
SOURCE
= 800 µA
V
CC
≥ 1.8 V, I
SINK
= 500 µA
V
CC
≥ 3.15 V, I
SINK
= 1.2 mA
V
CC
≥ 4.75 V, I
SINK
= 3.2 mA
MANUAL RESET INPUT (ADM6823/ADM6825)
MR Input Threshold
V
IL
V
IH
MR Input Pulse Width
MR Glitch Rejection
MR to Reset Delay
MR Pull-Up Resistance
0.3 × V
CC
0.7 × V
CC
1
100
200
50
25
75
V
V
µs
ns
ns
kΩ
Rev. B | Page 3 of 12
ADM6823/ADM6824/ADM6825
Parameter
WATCHDOG INPUT (ADM6823/ADM6824)
Watchdog Timeout Period
WDI Pulse Width
WDI Input Threshold
V
IL
V
IH
WDI Input Current
Min
1.12
50
Typ
1.6
Max
2.40
Unit
sec
ns
V
V
µA
µA
Data Sheet
Test Conditions/Comments
0.3 × V
CC
0.7 × V
CC
−20
120
−15
160
V
WDI
= V
CC
V
WDI
= 0
Rev. B | Page 4 of 12
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