April 2005
rev 1.3
ASM1834/A/D
Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset
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.
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.
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
3.3V
+5V
ASM1834
5V
IN
3.3V
IN
RESET
PBRST
5VTOL GND 3.3VTOL
3.3V
5V
µP
RESET
GND
Alliance Semiconductor
2575 Augustine Drive . Santa Clara, CA 95054 . Tel: 408.855.4900 . Fax: 408.855.4999 . www.alsc.com
Notice: The information in this document is subject to change without notice
ALSC [ ALLIANCE SEMICONDUCTOR CORPORATION ]
