19-1868; Rev 1; 1/01
Low-Voltage SOT23 µP Supervisors with
Manual Reset and Watchdog Timer
General Description
The MAX6821–MAX6825 are low-voltage microprocessor
(µP) supervisory circuits that combine voltage monitor-
ing, watchdog timer, and manual reset input functions in
a 5-pin SOT23 package. Microprocessor supervisory cir-
cuits significantly improve system reliability and accura-
cy compared to separate ICs or discrete components.
These devices assert a reset signal whenever the moni-
tored voltage drops below its preset threshold, keeping it
asserted for a minimum timeout period after V
CC
rises
above the threshold. In addition, a watchdog timer moni-
tors against code execution errors. A debounced manual
reset is also available. The MAX6821–MAX6825 monitor
voltages from +1.8V to +5.0V. These outputs are guaran-
teed to be in the correct state for V
CC
down to +1.0V.
Nine preprogrammed reset threshold voltages are
available (see
Threshold Suffix Guide).
The MAX6821,
MAX6822, and MAX6823 all have a manual reset input
and a watchdog timer. The MAX6821 has push-pull
RESET, the MAX6822 has open-drain
RESET,
and the
MAX6823 has push-pull
RESET.
The MAX6824 has a
watchdog timer and both push-pull
RESET
and push-
pull RESET. The MAX6825 has a manual reset input
and both push-pull
RESET
and push-pull RESET. The
Selector Guide
explains the functions offered in this
series of parts.
Features
o
Monitors +1.8V, +2.5V, +3.0V, +3.3V, +5.0V
Supplies
o
140ms (min) Reset Timeout Delay
o
1.6s Watchdog Timeout Period
(MAX6821/MAX6822/MAX6823/MAX6824)
o
Manual Reset Input
(MAX6821/MAX6822/MAX6823/MAX6825)
o
Three Reset Output Options
Push-Pull
RESET
Push-Pull RESET
Open-Drain
RESET
o
Guaranteed Reset Valid to V
CC
= +1.0V
o
Immune to Short Negative V
CC
Transients
o
No External Components
o
Small 5-Pin SOT23 Packages
MAX6821–MAX6825
Ordering Information
PART
*
MAX6821_UK-T
MAX6822_UK-T
MAX6823_UK-T
MAX6824_UK-T
MAX6825_UK-T
TEMP. RANGE
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
PIN-PACKAGE
5 SOT23-5
5 SOT23-5
5 SOT23-5
5 SOT23-5
5 SOT23-5
________________________Applications
Set-Top Boxes
Computers and
Controllers
Embedded Controllers
Intelligent Instruments
Automotive Systems
Critical µP Monitoring
Portable/Battery-
Powered Equipment
*Insert
the desired suffix letter (from the table below) into the blank
to complete the part number.
Threshold Suffix Guide
SUFFIX
L
RESET
THRESHOLD (V)
4.63
4.38
3.08
2.93
2.63
2.32
2.19
1.67
1.58
Pin Configurations
TOP VIEW
RESET(RESET)
1
5
V
CC
M
T
S
R
Z
Y
4
WDI
GND
2
MAX6821
MAX6822
MAX6823
MR
3
W
V
(RESET) MAX6821 ONLY
SOT23-5
Pin Configurations continued at end of data sheet.
Typical Operating Circuit appears at end of data sheet.
Note:
Bold indicates standard versions. Samples are typically
available for standard versions only. All parts require a 2.5k
minimum order increment. Contact factory for availability.
Selector Guide appears at end of data sheet.
1
________________________________________________________________
Maxim Integrated Products
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
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