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Product Description

The UM803 is a microprocessor (μP) supervisory circuit used to monitor the power supplies in μP and digital systems. It provides excellent circuit reliability and low cost by eliminating external components and adjustments when used with +5V, +3.3V, +3.0V or +2.5V powered circuits.

The circuit performs a single function: it asserts a reset signal whenever the VCCsupply voltage declines below a preset threshold, keeping it asserted for at least 140ms after VCChas risen above the reset threshold. Reset thresholds suitable for operation with a variety of supply voltages are available.

The UM803 has an open-drain output stage. The UM803’s open-drainRESET

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output requires a pull-up resistor that can be connected to a voltage higher than VCC. The UM803 has an active-lowRESET

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output. The reset comparator is designed to ignore fast transients on VCC, and the outputs are guaranteed to be in the correct logic state for VCCdown to 1V.

Low supply current makes the UM803 ideal for use in portable equipment. The UM803 is available in a 3-pin SOT323 and SOT23 package.

Features

- No External Components

- Power Supply Transient Immunity

- Guaranteed Reset Valid to VCC=+1V

- Precision VCCMonitoring of +2.5V, +3V, +3.3V and +5V Supplies

- Fully Specified Over Temperature

- 2μA Supply Current

- 140ms Minimum Power-On Reset Pulse Width

- Available in One Output Configuration:

Open-Drain Active-LowRESET

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Output

- 3-Pin SOT323 and SOT23 Packages

- Wide Operation Temperature: -40°C to +85°CApplications

- Computers

- Controllers

- Portable/Battery-Powered Equipments

- Intelligent Instruments

- Critical μP and μC Power Monitoring

- Automotive