Preliminary Technical Data
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
REF
V
CC
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 (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 (3 碌A)
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
04534-0-001
GND
WDI
Figure 1.
APPLICATIONS
Microprocessor systems
Computers
Controllers
Intelligent instruments
Portable equipment
GENERAL DESCRIPTION
The ADM823/ADM824/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.
Each part is 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 (min) and 1.6s (typ),
respectively.
The ADM823/ADM824/ADM825 are available in 5-lead SC70
and SOT-23 packages and typically consume only 3 碌A, making
them suitable for use in low power portable applications.
Table 1. Selection Table
Output Stage
Part No.
ADM823
ADM824
ADM825
Watchdog Timer
Yes
Yes
鈥?/div>
Manual Reset
Yes
鈥?/div>
Yes
RESET
Push-Pull
Push-Pull
Push-Pull
RESET
鈥?/div>
Push-Pull
Push-Pull
Rev.PrB
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 owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.326.8703
漏 2004 Analog Devices, Inc. All rights reserved.
1
2
3
4
5
6
7
8
9
10
