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Rev.1.9 Mar. 21, 2011

AX6901/2/3/4

3-Pin Microprocessor Reset Circuits



GENERAL DESCRIPTION

TheAX6901/2/3/4 is used for microprocessor (µP) supervisory circuits to monitor the

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, +3.3V, +3.0V,

+2.5V powered circuits.

These circuits perform a single function: they assert a reset signal whenever the VCC

supply voltage declines below a preset threshold, keeping it asserted for at least 200ms

after VCC has risen above the reset threshold. Reset thresholds suitable for operation with

a variety of supply voltages are available. TheAX6901/2/3/4 has push pull outputs.

TheAX6901/3 has an active low

RESET output, while theAX6902/4 has an active high

RESET 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 VCC down to 1.0V. Low supply

current makes theAX6901/2/3/4 ideal for use in portable equipment. TheAX6901/2/3/4 is

available in a 3-pin SOT23 and SC70 package.



FEATURES

- Precision Monitoring of +2.5,+3V, +3.3V, and +5V Power-Supply Voltages

- Fully Specified Over Temperature

- Available in Three Output Configurations

- Push-Pull

RESET Low Output(AX6901/3)

- Push-Pull RESET High Output(AX6902/4

- 200ms (Typ.)min Power-On Reset Pulse Width

- 25µA Supply Current

- Guaranteed Reset Valid to VCC = +1.0V

- Power Supply Transient Immunity

- No External Components

- Available in the 3-Pin Pb-Free SOT-23 and SC70 Package



BLOCK DIAGRAM

VREF

Delay

Circuit

RESET

/ RESET

GND

VCC

+

-

P-MOS

N-MOS