19-0487; Rev 4; 7/01
5-Pin Microprocessor Supervisory Circuits With
Watchdog Timer and Manual Reset
________________General Description
Features
The MAX823/MAX824/MAX825* microprocessor (µP)
supervisory circuits combine reset output, watchdog,
and manual reset input functions in 5-pin SOT23 and
SC70 packages. They significantly improve system relia-
bility and accuracy compared to separate ICs or discrete
components. The MAX823/MAX824/MAX825 are specifi-
o Precision Monitoring of +2.5V, +3V, +3.3V, and
+5V Power Supplies
o Operating Current: 6µA (MAX823L/M) (SC70)
2µA (MAX825T/S/R/Z/Y) (SC70)
o Fully Specified Over Temperature
o 140ms min Power-On Reset
cally designed to ignore fast transients on V
.
CC
Seven preprogrammed reset threshold voltages are
available (see Reset Threshold Table). All three devices
have an active-low reset output, which is guaranteed to
o Guaranteed RESET Valid to V
= 1V
CC
o Power-Supply Transient Immunity
o Watchdog Timer with 1.6s Timeout
be in the correct state for V
down to 1V. The MAX823
CC
(MAX823/MAX824)
also offers a watchdog input and manual reset input.
The MAX824 offers a watchdog input and a comple-
mentary active-high reset. The MAX825 offers a manual
reset input and a complementary active-high reset. The
Selector Guide explains the functions offered in this
series of parts.
o Manual Reset Input (MAX823/MAX825)
o No External Components
Ordering Information
†
PART
TEMP. RANGE
-40°C to +85°C
-40°C to +125°C
-40°C to +85°C
PIN-PACKAGE
5 SC70-5
*Patents Pending
________________________Applications
MAX823_EXK-T
MAX823_EUK-T
MAX824_EXK-T
5 SOT23-5
5 SC70-5
Computers and Controllers
Embedded Controllers
Intelligent Instruments
Automotive Systems
Critical µP Monitoring
Portable/Battery-Powered Equipment
†Insert the desired suffix letter (from the Reset Threshold table) into
the blank to complete the part number. All devices are available in
tape-and-reel only. There is a 2500 piece minimum order increment.
Ordering Information continued at end of data sheet.
______________________Selector Guide
Reset Threshold Table
RESET
THRESHOLD (V)
FUNCTION
MAX823
MAX824
MAX825
SUFFIX
✔
✔
✔
✔
—
✔
✔
Active-Low Reset
Active-High Reset
Watchdog Input
L
4.63
4.38
3.08
2.93
2.63
2.32
2.19
—
✔
✔
M
—
✔
T
Manual Reset Input
S
Typical Operating Circuit appears at end of data sheet.
Marking Information appears at end of data sheet.
R
Z (SC70 only)
Y (SC70 only)
Pin Configurations
TOP VIEW
1
2
3
5
4
V
1
2
3
5
4
1
2
3
5
RESET
GND
MR
RESET
GND
V
V
CC
RESET
GND
CC
CC
MAX823
MAX824
MAX825
WDI
RESET
WDI
4
MR
RESET
SOT23/SC70
SOT23/SC70
SOT23/SC70
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.