19-0411; Rev 3; 3/99
4-Pin 碌P Voltage Monitors
with Manual Reset Input
MAX811/MAX812
________________General Description
The MAX811/MAX812 are low-power microprocessor
(碌P) supervisory circuits used to monitor power sup-
plies in 碌P and digital systems. They provide excellent
circuit reliability and low cost by eliminating external
components and adjustments when used with 5V-
powered or 3V-powered circuits. The MAX811/MAX812
also provide a debounced manual reset input.
These devices perform a single function: They assert a
reset signal whenever the V
CC
supply voltage falls
below a preset threshold, keeping it asserted for at
least 140ms after V
CC
has risen above the reset thresh-
old. The only difference between the two devices is that
the MAX811 has an active-low RESET output (which is
guaranteed to be in the correct state for V
CC
down to
1V), while the MAX812 has an active-high RESET out-
put. The reset comparator is designed to ignore fast
transients on V
CC
. Reset thresholds are available for
operation with a variety of supply voltages.
Low supply current makes the MAX811/MAX812 ideal
for use in portable equipment. The devices come in a
4-pin SOT143 package.
____________________________Features
o
Precision Monitoring of 3V, 3.3V, and 5V
Power-Supply Voltages
o
6碌A Supply Current
o
140ms Min Power-On Reset Pulse Width;
RESET
Output (MAX811), RESET Output (MAX812)
o
Guaranteed Over Temperature
o
Guaranteed
RESET
Valid to V
CC
= 1V (MAX811)
o
Power-Supply Transient Immunity
o
No External Components
o
4-Pin SOT143 Package
_______________Ordering Information
PART*
MAX811_EUS-T
TEMP. RANGE
-40掳C to +85掳C
PIN-PACKAGE
4 SOT143
________________________Applications
Computers
Controllers
Intelligent Instruments
Critical 碌P and 碌C Power Monitoring
Portable/Battery-Powered Equipment
MAX812_EUS-T
-40掳C to +85掳C
4 SOT143
* This part offers a choice of five different reset threshold
voltages. Select the letter corresponding to the desired
nominal reset threshold voltage, and insert it into the blank
to complete the part number.
RESET THRESHOLD
SUFFIX
L
M
T
S
R
VOLTAGE (V)
4.63
4.38
3.08
2.93
2.63
___________
Typical Operating Circuit
V
CC
V
CC
V
CC
___________________Pin Configuration
TOP VIEW
GND
1
4
V
CC
MAX811
MAX812
MR
GND
RESET
(RESET)
碌P
RESET
INPUT
(RESET) RESET
GND
2
MAX811
MAX812
3
MR
PUSHBUTTON
SWITCH
SOT143
( ) ARE FOR MAX812
( ) ARE FOR MAX812
NOTE: SEE LAST PAGE FOR MARKING INFORMATION.
________________________________________________________________
Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.