ASM802LAEPA ALSC [Alliance Semiconductor Corporation], ASM802LAEPA Datasheet

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ASM802LAEPA

Manufacturer Part Number
ASM802LAEPA
Description
UP Power Supply Supervisor With Battery Backup Switch
Manufacturer
ALSC [Alliance Semiconductor Corporation]
Datasheet
rev 1.0
October 2003
General Description
The AS690A / AS692A / AS802L / AS802M / AS805L 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,
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:
These features are pin-compatible with the industry standard
power-supply supervisors. Short-circuit and thermal protection
have also been added. The AS690A / AS802L /
generate a reset pulse when the supply voltage drops below
4.65V and the AS692A / AS802M 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
1.6 second watchdog timer to keep microprocessor
responsive
4.40V or 4.65V V
power-up and power-down
SPDT (Single-pole, Double-throw) PMOS switch connects
backup power to RAM if V
1.25V threshold detector for power loss or general purpose
voltage monitoring
Two precision supply-voltage monitor options
•4.65V (AS690A / AS802L / AS805L)
•4.40V (AS692A / AS802M )
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 package
No external components
Specified over full temperature range
battery-backup
2575 Augustine Drive . Santa Clara, CA 95054 . Tel: 408.855.4900 . Fax: 408.855.4999 . www.alsc.com
CC
threshold for microprocessor reset at
µP Power Supply Supervisor With Battery Backup Switch
CC
switching
Notice: The information in this document is subject to change without notice
fails
and
power-failure
AS805L
Alliance Semiconductor
Applications
Typical Operating Circuit
Block Diagram
V
V
WDI
WDI
BATT
BATT
V
V
PFI
PFI
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
CC
CC
8
8
Unregulated DC
2
2
6
6
4
4
R
R
2
1
ASM690A, ASM692A, ASM802L, ASM802M, (ASM805L)
+
_
3.6 V
Lithium
Battery
0.1 µF
Battery-Switchover Circuit
Battery-Switchover Circuit
|+
|+
1.25V
1.25V
3.5V
3.5V
|+
|+
ASM690A
V
GND
PFI
BATT
+
+
-
-
|+
|+
0.8V
0.8V
3
+
+
-
-
V
ASM690A / 692A
ASM802L / 802M
CC
GND
V
RESET
-
-
+
+
OUT
Regulated +5V
WDI
PFO
1.25V
1.25V
|+
|+
Generator
Generator
Watchdog
Watchdog
Reset
Reset
Timer
Timer
GND
-
-
+
+
RESET
ASM805L
NMI
I/O LINE
V
CC
GND
CMOS
V
RAM
CC
1
1
7
7
5
5
(RESET)
(RESET)
V
V
RESET
RESET
PFO
PFO
OUT
OUT

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ASM802LAEPA Summary of contents

Page 1

October 2003 rev 1.0 µP Power Supply Supervisor With Battery Backup Switch General Description The AS690A / AS692A / AS802L / AS802M / AS805L offers complete single chip solutions for power supply monitoring and control battery functions in microprocessor systems. ...

Page 2

October 2003 rev 1.0 Pin Configuration Pin Description Pin Number ASM690A / Name ASM692A ASM805L ASM802L / ASM802M RESET - 7 RESET µP ...

Page 3

October 2003 rev 1.0 Detailed Description It is important to initialize a microprocessor to a known state in response to specific events that could create code execution errors and “lock-up”. The reset output of these supervisory circuits send a reset ...

Page 4

October 2003 rev 1.0 Watchdog Input As discussed in the Reset section, the Watchdog input is used to monitor microprocessor activity. It can be used to insure that the microprocessor continually responsive state by requiring that the ...

Page 5

October 2003 rev 1.0 Backup Power Sources - Batteries Battery voltage selection is important to insure that the battery does not discharge through the parasitic device diode D1 (see Figure 3) when V is less than ...

Page 6

October 2003 rev 1.0 Operation without a Backup Power Source When operating without a back-up power source, the V pin should be connected to GND and V connected since power source switchover will not CC occur. Connecting ...

Page 7

October 2003 rev 1.0 Monitoring Capabilities Of The Power-fail Input: Although designed for power supply failure monitoring, the PFI pin can be used for monitoring any voltage condition that can be scaled by means of a resistive divider. An example ...

Page 8

October 2003 rev 1.0 Absolute Maximum Ratings Parameter Pin Terminal Voltage with Respect to Ground BATT All other inputs * Input Current Input Current at V BATT Input Current at GND Output Current V ...

Page 9

October 2003 rev 1.0 Electrical Characteristics: Unless other wise noted 4.75V to 5.5V for the ASM690A / ASM802L / ASM805L and 2.8V; and BATT A MIN MAX Parameter ...

Page 10

October 2003 rev 1.0 Parameter Symbol Reset Threshold Hysteresis t Reset Pulse Width RS I SOURCE I SINK ASM69_AC, ASM802_C SINK ASM69_AE, ASM802_E, V Reset Output Volt- I age SINK ASM805LC, I ASM805LE, I ASM805L, I ASM805L, I ...

Page 11

October 2003 rev 1.0 Plastic DIP (8-Pin) CerDIP (8-Pin) SO (8-Pin) µP Power Supply Supervisor With Battery Backup Switch Notice: The information in this document is subject to change without notice ASM690A / 692A ASM802L / 802M Package Information Inches ...

Page 12

... ASM690ACSA 4.5 TO 4.75 ASM690AC/D 4.5 TO 4.75 ASM690AEPA ASM690AESA 4.5 TO 4.75 ASM690AMJA 4.5 TO 4.75 ASM692A ASM692ACPA 4.25 TO 4.50 ASM692ACSA 4.25 TO 4.50 ASM692AC/D 4.25 TO 4.50 ASM692AEPA 4.25 TO 4.50 ASM692AESA 4.25 TO 4.50 ASM692AMJA 4.25 TO 4.50 ASM802L ASM802LCPA 4.5 TO 4.75 ASM802LCSA 4.5 TO 4.75 ASM802LAEPA 4.5 TO 4.75 ASM802LESA 4.5 TO 4.75 ASM802M ASM802MCPA 4.25 TO 4.50 ASM802MCSA 4.25 TO 4.50 ASM802MEPA 4.25 TO 4.50 ASM802MESA 4.25 TO 4.50 ASM805L ASM805LCPA 4.5 TO 4.75 ASM805LCSA 4.5 TO 4.75 ASM805LC/D 4.5 TO 4.75 ASM805LEPA 4.5 TO 4.75 ASM805LESA 4.5 TO 4.75 ASM805LMJA 4.5 TO 4.75 µP Power Supply Supervisor With Battery Backup Switch Notice: The information in this document is subject to change without notice ...

Page 13

October 2003 rev 1.0 Alliance Semiconductor Corporation 2575, Augustine Drive, Santa Clara, CA 95054 Tel: 408 - 855 - 4900 Fax: 408 - 855 - 4999 www.alsc.com © Copyright 2003 Alliance Semiconductor Corporation. All rights reserved. Our three-point logo, our ...

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