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Notice: The information in this document is subject to change without notice

4 Pin µP Voltage Supervisor with Manual Reset

ASM811, ASM812

October 2003

rev 1.0

Pin Diagram:

Block Diagram

Pin Description

Pin #

Pin

Name

Function

ASM811

ASM812

1

1

GND

Ground.

2

-

RESET

the Threshold. In addition, RESET is active LOW as long as the manual reset is low.

-2

RESET

the threshold. In addition, RESET is active HIGH as long as the manual reset is low.

33

MR

Manual Reset Input. A logic LOW on MR asserts reset. Reset remains active as long as MR is

resistor. The input should be left open if not used. It can be driven by TTL or CMOS logic or

shorted to ground by a switch.

44

Power supply input voltage (3.0V, 3.3V, 5.0V)

Detailed Description

A

proper

reset

input

enables

a

microprocessor

/

microcontroller to start in a known state. ASM811/812 assert

reset to prevent code execution errors during power-up, power-

down and brown-out conditions.

Reset Timing

The reset signal is asserted- LOW for the ASM811 and HIGH

threshold trip voltage and remains asserted for 140ms

Manual Reset (MR) Input

A logic low on MR assserts RESET LOW on the ASM811 and

RESET HIGH on the ASM812. MR is internally pulled high

through a 20k

Ω resistor and can be driven by TTL/CMOS gates

or with open collector/drain outputs. MR can be left open if not

used. MR may be connected to ground through a normally-

open momentary switch without an external debounce circuit.

A 0.1µF capacitor from MR to ground can be added for

additional noise immunity.

1

2

3

SOT143

ASM811

(ASM812)

GND

RESET

(RESET)

4

MR

+

-

RESET Generator

-

+

RESET

(RESET)

GND

ASM811

(ASM812)

4.38V

4.00V

3.08V

2.93V

2.63V

4.38V

4.63V

MR

20k

Ω