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19-0411; Rev 6; 5/18
General Description
The MAX811/MAX812 are low-power microprocessor
(μP) supervisory circuits used to monitor power supplies
in μP and digital systems. They provide excellent circuit
reliability and low cost by eliminating external compo-
nents and adjustments when used with 5Vpowered 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 threshold. 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 output. 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.
Applications
● Computers
● Controllers
● Intelligent Instruments
● Critical μP and μC Power Monitoring
● Portable/Battery-Powered Equipment
Benets and Features
● Integrated Voltage Monitor Increases System
Robustness with Added Manual Reset
• Precision Monitoring of 3V, 3.3V, and 5V
Power-Supply Voltages
• 140ms Min Power-On-Reset Pulse Width
• RESET Output (MAX811), RESET Output
(MAX812)
• Guaranteed Over Temperature
• Guaranteed RESET Valid to V
CC
= 1V (MAX811)
• Power-Supply Transient Immunity
● Saves Board Space
• No External Components
• 4-Pin SOT143 Package
● Low Power Consumption Simplifies Power-Supply
Requirements
• 6μA Supply Current
*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.
Devices are available in both leaded and lead(Pb)-free packaging.
Specify lead-free by replacing “-T” with “+T” when ordering.
RESET THRESHOLD
SUFFIX VOLTAGE (V)
L
4.63
M
4.38
T
3.08
S
2.93
R
2.63
PART* TEMP RANGE PIN-PACKAGE
MAX811_EUS-T -40°C to +85°C 4 SOT143
MAX812_EUS-T -40°C to +85°C 4 SOT143
MAX811
MAX812
V
CC
V
CC
RESET
(RESET)
RESET
INPUT
GND
V
CC
GND
µP
( ) ARE FOR MAX812
PUSHBUTTON
SWITCH
MR
1
2
4
3
V
CC
MR(RESET) RESET
GND
MAX811
MAX812
SOT143
TOP VIEW
( ) ARE FOR MAX812
NOTE: SEE PACKAGE INFORMATION FOR MARKING INFORMATION.
MAX811/MAX812 4-Pin μP Voltage Monitors
with Manual Reset Input
Typical Operating Circuit Pin Conguration
Ordering Information
Click here for production status of specic part numbers.
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