UM805 Datasheet, PDF (1/14 Pages) Union Semiconductor, Inc. – Voltage Monitors with Manual Reset Input

UM805/811/812
4-Pin μP Voltage Monitors with Manual Reset Input
UM805/811/812 SOT143
General Description
The UM805/811/812 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 5V-powered or 3V-powered
circuits. The UM805/811/812 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. Reset thresholds are available for operation with a variety of supply voltages.
The UM805 has an open-drain output stage, while the UM811/812 have push-pull outputs. The
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UM805’s open-drain RESET output requires a pull-up resistor that can be connected to a voltage
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higher than V_CC. The UM805/811 have an active-low RESET output, while the UM812 has an
active-high RESET output. The reset comparator is designed to ignore fast transients on V_CC, and
the outputs are guaranteed to be in the correct logic state for V_CC down to 1V.
Low supply current makes the UM805/811/812 ideal for use in portable equipments. The devices
come in a 4-pin SOT143 package.
Applications
Features
 Computers
 No External Components
 Controllers
 V_CC Transient Immunity
 Portable/Battery-Powered Equipments  Correct Logic Output Guaranteed to V_CC=1.0V
 Intelligent Instruments
 Precision V_CC Monitoring of 3.0V, 3.3V and 5.0V
 Critical μP and μC Power Monitoring
Supplies
 2μA Supply Current
 140ms Minimum Power-On Reset Pulse Width
 Guaranteed Over Temperature
 Available in 3 Output Configurations:
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Open-Drain Active-Low RESET Output(UM805)
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Push-Pull Active-Low RESET Output(UM811)
Push-Pull Active-High RESET Output(UM812)
 4-Pin SOT143 Package
 Wide Operation Temperature: -40°C to +85°C
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http://www.union-ic.com Rev.01 Jan.2015
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