19-0411; Rev 4; 12/05
4-Pin µP Voltage Monitors
with Manual Reset Input
____________________________Features
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
components and adjustments when used with 5Vpowered or 3V-powered circuits. The MAX811/MAX812
also provide a debounced manual reset input.
♦ Precision Monitoring of 3V, 3.3V, and 5V
Power-Supply Voltages
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 VCC 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 VCC down to
1V), while the MAX812 has an active-high RESET output. The reset comparator is designed to ignore fast
transients on VCC. 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
♦ 6µA Supply Current
♦ 140ms Min Power-On Reset Pulse Width;
RESET Output (MAX811), RESET Output (MAX812)
♦ Guaranteed Over Temperature
♦ Guaranteed RESET Valid to VCC = 1V (MAX811)
♦ Power-Supply Transient Immunity
♦ No External Components
♦ 4-Pin SOT143 Package
_______________Ordering Information
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
*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-free packaging.
Specify lead-free by replacing “-T” with “+T” when ordering.
Controllers
RESET THRESHOLD
Intelligent Instruments
SUFFIX
VOLTAGE (V)
Critical µP and µC Power Monitoring
L
4.38
T
3.08
S
2.93
R
___________Typical Operating Circuit
4.63
M
Portable/Battery-Powered Equipment
2.63
___________________Pin Configuration
TOP VIEW
VCC
VCC
VCC
MAX811
MAX812
GND
1
μP
RESET
(RESET)
MR
VCC
3
MR
MAX811
MAX812
RESET
INPUT
(RESET) RESET
GND
4
2
GND
SOT143
PUSHBUTTON
SWITCH
( ) ARE FOR MAX812
( ) ARE FOR MAX812
NOTE: SEE LAST PAGE FOR MARKING INFORMATION.
________________________________________________________________ Maxim Integrated Products
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.
1
MAX811/MAX812
________________General Description
