ASM690A Datasheet, PDF (1/15 Pages) PulseCore Semiconductor – μP Power Supply Supervisor With Battery Backup Switch

April 2008
rev 1.7
ASM690A/692A
ASM802L/802M
ASM805L
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
• 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
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.
Block Diagram
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
PulseCore Semiconductor Corporation
1715 S. Bascom Ave Suite 200 Campbell, CA 95008 • Tel: [phone] • Fax: [phone]
www.pulsecoresemi.com
Notice: The information in this document is subject to change without notice.