FM1233ADS3X(2001) 查看數據表（PDF） - Fairchild Semiconductor

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FM1233ADS3X
(Rev.:2001)

3-Pin µC Supervisor Circuit

Fairchild Semiconductor 

November 2001

FM1233A

3-Pin µC Supervisor Circuit

General Description

The FM1233A is a supervisor circuit that monitors a microproces-

sor power supply or other system voltage and issues a reset pulse

when a fault condition exists. Several different threshold voltages

are offered to accommodate 3V systems with different tolerances.

The device features a precision temperature-compensated volt-

age reference and comparator. When VCC falls to the threshold

voltage, a RESET pulse is issued, holding the output in the active

state. When power rises above VTH, the reset remains for approxi-

mately 250 ms to allow the system clock and other circuits to

stabilize. The reset output of FM1233A is of open-drain active low

type.

The FM1233A also can monitor a switch closure on its output,

enabling it to recognize an external reset from a pushbutton switch

or a µP. In the case of a switch, the closure will be debounced by

circuitry internal to the FM1233A.

Typical Operating Circuit

VCC

Features

I Precision monitoring of 3.3V and lower voltage

microprocessor systems

I VTH values of 2.88V, 2.72V

I Automatic restart of microprocessor after power failure

I 140ms (min) power-on RESET delay (typ.: 256ms)

I Internal 5kΩ pull-up resistor

I Other reset choices available: 32 to 128ms

I Operating Temperature -40°C to +105°C

I Monitors external pushbutton override

I Internal switch debounce circuitry

I SOT23-3 package

3

FM1233A

Controller

GND

1

2

/RESET

Connection Diagram

GND 1

FM1233A 3 VCC

/RESET 2

SOT23-3 Package

© 2001 Fairchild Semiconductor Corporation

1

FM1233A Rev. B

www.fairchildsemi.com

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