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

Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset

rev 1.5

November 2006

ASM1834/A/D

PulseCore Semiconductor Corporation

1715 S. Bascom Ave Suite 200 Campbell, CA 95008

• Tel: 408-879-9077 • Fax: 408-879-9018

www.pulsecoresemi.com

General Description

The ASM1834 supervisors simultaneously monitor both 3.3V

and 5V power sources and generate reset signals when either

supply is out of tolerance. When an out-of-tolerance condition is

detected, the output-reset signal of the affected supply

becomes active and resets the system microprocessor/

microcontroller. On power-up and after the supply voltage

returns to an in-tolerance condition, the reset signal remains

active for approximately 350ms. This allows the power supply

and system microprocessor to stabilize.

Tolerance levels are independently selectable for both supplies.

Tolerance options are 5% and 10% percent for the 5V supply

and 10% and 20% percent for the 3.3V supply.

The ASM1834 and ASM1834D have push-pull reset output

stages. The ASM1834A reset outputs are open drain devices

that can both be connected to either 5V or 3.3V supply. The

ASM1834 and ASM1834A have active LOW reset outputs. The

ASM1834D has active HIGH reset outputs.

All devices can generate reset signals through an internally

debounced pushbutton reset input that affects both reset

outputs.

All devices operate over the extended industrial temperature

range. Devices are available in 8-pin DIP, surface mount 8-pin

SO and 8-Pin MicroSO packages. Die are also available.

Key Features

•

Monitors 5V and 3.3V supplies simultaneously

•

5V and 3.3V power-on reset

•

350ms reset time

•

Debounced pushbutton reset input

•

Push-pull CMOS output

• ASM1834, ASM1834D

• Eliminates external pull-up resistors

• Active LOW (ASM1834), HIGH (ASM1834D)

•

Open Drain Output

• ASM1834A

• Active LOW

•

Selectable 5V and 3.3V trip point tolerance

•

Internal power drawn from highest input voltage, 5V or

3.3V

•

Precision temperature-compensated voltage reference and

comparator

•

Low cost surface mount SO, compact MicroSO and DIP

packages.

•

Wide operating temperature, -40°C to +85°C

Applications

•

Microprocessors

•

PDAs, Hand-held PCs

•

Embedded Controllers

•

Telecommunication Systems

•

Power Supplies

•

Wireless / Cellular Systems

•

Networking Hardware

Typical Operating Circuit

+5V

3.3V

RESET

PBRST

5VTOL

GND

3.3VTOL

RESET

GND

µP

3.3V

5V

ASM1834