February 2005
rev 1.4
ASM1811
Low Power 5V µP Reset Active LOW, Open - Drain Output
Applications
•
•
•
•
•
•
•
Set-top boxes
Cellular phones
PDAs
Energy management systems
Embedded control systems
Printers
Single board computers
General Description
The ASM1811 is a voltage supervisory device with a low-power,
5V µP Reset, active LOW, open-drain output. Maximum supply
current over temperature is a low 20µA.
The ASM1811 generates an active LOW reset signal whenever
the monitored supply is out of tolerance. A precision reference
and comparator circuit monitor power supply (V
CC
) level.
Tolerance level options are 5%, 10% and 15%. When an out-of-
tolerance condition is detected, an internal power-fail signal is
generated which forces an active LOW reset signal. After V
CC
returns to an in-tolerance condition, the reset signal remains
active for 150ms to allow the power supply and system
microprocessor to stabilize.
Typical Operating Circuit
V
CC
ASM1811
The ASM1811 is designed with a open-drain output stage and
operates over the extended industrial temperature range.
Devices are available in low cost TO-92 and compact surface
mount SOT-23 packages.
Other low power products in this family include the ASM1810/
12/15/16/17, ASM1233D and ASM1233M.
RESET
Microprocessor
RESET
GND
Key Features
•
•
•
•
•
•
•
•
Low Supply Current
•20 µA maximum (5.5 V)
Automatically restarts a microprocessor after power failure
150ms reset delay after V
CC
returns to an in-tolerance con-
dition
Active LOW power-up reset
Precision temperature-compensated voltage reference and
comparator
Eliminates external components
Low cost TO-92 and compact surface mount SOT-23 pack-
ages
Operating temperature -40°C to +85°C
Block Diagram
V
CC
2
Supply
Tolerance
Bias
ASM1811
5.5K
Ω
1
RESET
+
-
Reference
Delay
150ms
Typical
3
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
February 2005
rev 1.4
ASM1811
Application Information
Operation - Power Monitor
The
ASM1811
detects
out-of-tolerance
power
supply
conditions. It resets a processor during power-up, power-
down and issues a reset to the system processor when the
monitored power supply voltage is below the reset threshold.
When an out-of-tolerance V
CC
voltage is detected, the
RESET signal is asserted. On power-up, RESET is kept
voltage has reached the selected tolerance. This allows the
power supply and microprocessor to stabilize before RESET
is released.
RESET
V
CC
V
CCTP
(MAX)
V
CCTP
V
CCTP
(MIN)
t
F
t
RPD
t
R
V
CCTP
(MAX)
V
CCTP
(MIN)
V
CCTP
V
OL
Figure 2: Timing Diagram: Power-Down
V
CC
t
RPU
V
OH
RESET
Figure 1: Timing Diagram: Power-Up
~
~
3 of 9
active (LOW) for approximately 150ms after the power supply
~
~
~
~
Low Power 5V µP Reset
Notice: The information in this document is subject to change without notice
February 2005
rev 1.4
ASM1811
Absolute Maximum Ratings
Parameter
Voltage on V
CC
Voltage on RESET
Operating Temperature Range
Soldering Temperature (for 10 sec)
Storage Temperature
-55
Min
-0.5
-0.5
-40
Max
7
V
CC
+ 0.5
85
260
125
Unit
V
V
°C
°C
°C
ESD rating
HBM
MM
2
200
KV
V
NOTE: These are stress ratings only and functional use is not implied. Exposure to absolute maximum ratings for prolonged
periods of time may affect device reliability.
Electrical Characteristics
Unless otherwise noted, V
CC
= 1.2V to 5.5V and specifications are over the operating temperature range of -40°C to +85°C. All voltages are
referenced to ground
Parameter
Supply Voltage
Operating Current
V
CC
Trip Point (ASM1811R-5)
V
CC
Trip Point (ASM1811R-10)
V
CC
Trip Point (ASM1811R-15)
Internal Pull-up Resistor
Output Capacitance
RESET Active Time
V
CC
Detect to RESET Low
V
CC
Slew Rate
(V
CCTP
(MAX) to V
CCTP
(MIN)
V
CC
Slew Rate
(V
CCTP
(MIN) to V
CCTP
(MAX)
V
CC
Detect to RESET High
Symbol
V
CC
I
CC
V
CCTP
V
CCTP
V
CCTP
R
P
C
OUT
t
RESET
t
RPD
t
F
t
R
t
RPU
t
r
= 5µs
Conditions
Min
1.2
Typ
Max
5.5
Unit
V
µA
V
V
V
kΩ
pF
ms
µs
µs
V
CC
< 5.5V, RESET output open
4.50
4.25
4.00
3.5
8
4.62
4.35
4.13
5.5
20
4.75
4.49
4.24
7.5
10
100
150
2
250
5
300
0
100
150
300
ns
ms
Note: The t
F
value is for reference in defining values for t
RPD
and should not be considered for proper operation or use.
4 of 9
Low Power 5V µP Reset
Notice: The information in this document is subject to change without notice
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