ASM690A/692A

ASM802L/802M

April 2008

ASM805L

rev 1.7

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

PulseCore Semiconductor Corporation

1715 S. Bascom Ave Suite 200 Campbell, CA 95008

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

www.pulsecoresemi.com

µP Power Supply Supervisor With Battery Backup Switch

General Description

The ASM690A / ASM692A / ASM802L / ASM802M /

ASM805L offers complete single chip solutions for power

supply monitoring and control battery functions in

microprocessor systems. Each device implements four

functions: Reset control, watchdog monitoring, battery-

backup switching and powerfailure monitoring. In addition

to microprocessor reset under power-up and power-down

conditions,

these

devices

provide

battery-backup

switching to maintain control in power loss and brown-out

situations. Additional monitoring capabilities can provide

an early warning of unregulated power supply loss before

the voltage regulator drops out. The important features of

these four functions are:

• 1.6 second watchdog timer to keep microprocessor

responsive

• 4.40V or 4.65V VCC threshold for microprocessor reset

at power-up and power-down

• SPDT (Single-pole, Double-throw) PMOS switch

connects backup power to RAM if VCC fails

• 1.25V threshold detector for power loss or general

purpose voltage monitoring

These features are pin-compatible with the industry

standard power-supply supervisors. Short-circuit and

thermal protection have also been added. The ASM690A

/ ASM802L / ASM805L generate a reset pulse when the

supply voltage drops below 4.65V and the ASM692A /

ASM802M generate a reset below 4.40V. The ASM802L /

ASM802M have power-fail accuracy to ± 2%. The

ASM805L is the same as the ASM690A except that

RESET is provided instead of RESET.

Features

• Two precision supply-voltage monitor options

4.65V (ASM690A / ASM802L / ASM805L)

4.40V (ASM692A / ASM802M )

• Battery-backup power switch on-chip

• Watchdog timer: 1.6 second timeout

• Power failure / low battery detection

• Short circuit protection and thermal limiting

• Small 8-pin SO and 8-pin PDIP packages

• No external components

• Specified over full temperature range

Applications

• Embedded control systems

• Portable/Battery operated systems

• Intelligent instruments

• Wireless instruments

• Wireless communication systems

• PDAs and hand-held equipments

• µP / µC power supply monitoring

• Safety system

Typical Operating Circuit

Block Diagram