LM809

RESET

RESET

INPUT

GND

GND

V

CC

V

CC

V

CC

µP

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An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,

intellectual property matters and other important disclaimers. PRODUCTION DATA.

LM809, LM810

SNVS052E – SEPTEMBER 1999 – REVISED APRIL 2016

LM809/LM810 3-Pin Microprocessor Reset Circuits

1

1 Features

1

•

Precision Monitoring of Supply Voltages

–

Available Threshold Options:

2.63 V, 2.93 V, 3.08 V, 4.38 V, 4.63 V

•

Superior Upgrade to MAX809 and MAX810

•

Fully Specified Over Temperature

•

140-ms Minimum Power-On Reset Pulse Width,

240-ms Typical

–

Active-Low RESET Output (LM809)

–

Active-High RESET Output (LM810)

•

Ensured RESET Output Valid for VCC ≥ 1 V

•

Low Supply Current, 15-µA Typical

•

Power Supply Transient Immunity

2 Applications

•

Factory Automation

•

Building Automation

•

Programmable Logic Control

•

Renewable Energy

•

Microprocessor Systems

•

Computers

•

Controllers

•

Intelligent Instruments

•

Portable/Battery-Powered Equipment

•

Automotive

3 Description

The LM809 and LM810 microprocessors supervisory

circuits can be used to monitor the power supplies in

microprocessor and digital systems. They provide a

reset to the microprocessor during power-up, power-

down and brown-out conditions.

The function of the LM809 and LM810 are to monitor

the VCC supply voltage, and assert a reset signal

whenever this voltage declines below the factory-

programmed

reset

threshold.

The

reset

signal

remains asserted for 240 ms after VCC rises above

the threshold. The LM809 has an active-low RESET

output, while the LM810 has an active-high RESET

output.

Seven standard reset voltage options are available,

suitable for monitoring 5-V, 3.3-V, and 3-V supply

voltages.

With a low supply current of only 15 µA, the LM809

and LM810 are ideal for use in portable equipment.

Device Information(1)

PART NUMBER

PACKAGE

BODY SIZE (NOM)

LM809, LM810

SOT-23 (3)

2.92 mm × 1.30 mm

(1) For all available packages, see the orderable addendum at

the end of the data sheet.

Typical Application for Microprocessor Reset Circuit