©2005 Fairchild Semiconductor Corporation

1

www.fairchildsemi.com

August 2005

FM809/810 Rev. G

FM809/810

3-Pin µC Supervisor Circuits

General Description

The FM809/810 are supervisor circuits that monitor power

supply or other system voltages and issue reset pulse whenever

the voltage being monitored is out of tolerance. Once asserted,

the reset pulse is guaranteed to be valid for a minimum of

140ms (256ms typical). FM809xx offers active low push-pull

type of reset while FM810xx offers active high push-pull type.

Several threshold voltages are offered to accommodate 5.0V,

3.3V, 3.0V and 2.7V system voltages.

The low supply current (typically 2 µA)recommends FM809/810

devices for portable designs or wherever power saving is

primary.

These devices are offered in space saving 3-pin SOT23 and

SC70 packages.

Features

■ RESET (FM809) or RESET (FM810) output

■ 140ms power-on RESET delay (minimum)

■ RESET operation guaranteed to 1.0V

■ Supply current only 2µA

■ No external components

■ Operating Range

– -40°C to +105°C (SOT23)

– -40°C to +85°C (SC70)

■ SOT23-3 and SC70-3 packages

Applications

■ Microcontrollers and Microprocessors

■ Appliances

■ Power-Supply Monitoring

■ Portable Equipment

■ Automotive Systems

Typical Operating Circuit

Connection Diagram

SOT23-3 & SC70-3Packages

FM809

µC

GND

GND

RESET

I/P

RESET

3

GND

RESET (809) or

RESET (810)

1

2

FM809/810