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MAX811/MAX812
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 components 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 VCC 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
●● Controllers
●● Intelligent Instruments
●● Critical μP and μC Power Monitoring
●● Portable/Battery-Powered Equipment
Typical Operating Circuit
VCC
VCC MAX811 MAX812
RESET MR (RESET)
GND
VCC µP RESET INPUT
GND
PUSHBUTTON SWITCH
( ) ARE FOR MAX812
4-Pin μP Voltage Monitors with Manual Reset Input
Benefits 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 VCC = 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
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(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
Pin Configuration
TOP VIEW
GND 1
MAX811 MAX812
4 VCC
(RESET) RESET 2
3 MR
SOT143 ( ) ARE FOR MAX812
NOTE: SEE PACKAGE INFORMATION FOR MARKING INFORMATION.
19-0411; Rev 6; 5/18
MAX811/MAX812
4-Pin μP Voltage Monitors with Manual Reset Input
Absolute Maximum Ratings
Terminal Voltage (with respect to GND) VCC.....................................................................-0.3V to 6.0V All Other Inputs..................................... -0.3V to (VCC + 0.3V)
Input Current, VCC, MR......................................................20mA Output Current, RESET or RESET.....................................20mA Continuous Power Dissipation (TA = +70°C)
SOT143 (derate 4mW/°C above +70°C)......................320mW
Operating Temperature Range........................... -40°C to +85°C Junction Temperature......................................................+150°C Storage Temperature Range............................. -65°C to +160°C Lead Temperature (soldering, 10sec).............................. +300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Electrical Characteristics
(VCC = 5V for L/M versions, VCC = 3.3V for T/S versions, VCC = 3V for R version, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER Operating Voltage Range Supply Current
Reset Threshold
Reset Threshold Tempco
SYMBOL VCC ICC
VTH
CONDITIONS
TA = 0°C to +70°C
TA = -40°C to +85°C
MAX81_L/M, VCC = 5.5V, IOUT = 0
MAX81_R/S/T, VCC = 3.6V, IOUT = 0
MAX81_L
TA = +25°C TA = -40°C to +85°C
MAX81_M
TA = +25°C TA = -40°C to +85°C
MAX81_T
TA = +25°C TA = -40°C to +85°C
MAX81_S
TA = +25°C TA = -40°C to +85°C
MAX81_R
TA = +25°C TA = -40°C to +85°C
MIN 1.0 1.2
4.54 4.50 4.30 4.25 3.03 3.00 2.88 2.85 2.58 2.55
TYP
6 2.7 4.63 4.38 3.08 2.93 2.63 30
MAX 5.5
15 10 4.72 4.75 4.46 4.50 3.14 3.15 2.98 3.00 2.68 2.70
UNITS V µA
V
ppm/°C
VCC to Reset Delay (Note 2)
Reset Active Timeout Period MR Minimum Pulse Width MR Glitch Immunity (N.