ASM1233A
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
rev 1.0 Low Power, 3.3V, µP Reset, Active LOW, Open-Drain Output
November 2003
General Description
The ASM1233A is a voltage supervisor with low-power, 3.3V
µP Reset, with an active LOW, open-drain output. Maximum
supply current over temperature is a low 15µA.
The ASM1233A generates an active LOW reset signal
whenever the monitored supply is out of tolerance. A precision
reference and comparator circuit monitor power supply (VCC)
level. The tolerance is 15% for the 3.3V, ASM1233A. When an
out-of-tolerance condition is detected, an internal power-fail
signal is generated which forces an active LOW reset signal.
After VCC returns to an in-tolerance condition, the reset signal
remains active for 350ms to allow the power supply and system
microprocessor to stabilize.
The ASM1233A is designed with a open-drain output stage and
operates over the extended industrial temperature range.
Devices are available in compact SOT-223 packages.
Other low power products in this family include the ASM1810/
11/12/15/16/17, ASM1233D, and ASM1233M
Key Features
• Low Supply Current
•15µA maximum (3.6 V)
• Automatically restarts a microprocessor after power failure
• 350ms reset delay after VCC returns to an in-tolerance con-
dition
• Active LOW power-up reset, 5kΩ internal pull-up
• Precision temperature-compensated voltage reference and
comparator
• Eliminates external components
• Low-cost SOT-223 package
• Operating temperature -40°C to +85°C
Applications
• Set-top boxes
• Cellular phones
•PDAs
• Energy management systems
• Embedded control systems
• Printers
• Single board computers
Typical Operating Circuit
Block Diagram
GND
Supply
Reference
Delay
350ms
Typical
Tolerance
Bias
+
-
Microprocessor
ASM1233A
VCC
RESET
Delay
Typical
+
-
VCC
RESET RESET
GND
ASM1233A
5.0kΩ
ASM1233A
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Notice: The information in this document is subject to change without notice
Low Power, 3.3V, µP Reset, Active LOW, Open-Drain Output
rev 1.0
November 2003
Pin Configuration
Pin Description
Pin# Pin Name Description
1 GND Ground.
2 RESET Active LOW reset output.
3VCC Power supply input.
4 GND Ground.
ASM1233A
SOT-223
1
2
3
4
GND
RESET
VCC
GND
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Notice: The information in this document is subject to change without notice
Low Power, 3.3V, µP Reset, Active LOW, Open-Drain Output
ASM1233A
rev 1.0
November 2003
Application Information
Operation - Power Monitor
The ASM1233A detects out-of-tolerance power supply
conditions. It resets a processor during power-up, power-
down and generates a reset to the system processor when
the monitored power supply voltage is below the reset
threshold. When an out-of-tolerance VCC voltage is detected,
the RESET signal is asserted. On power-up, RESET is kept
active (LOW) for approximatley 350ms after the power supply
voltage has reached the selected tolerance. This allows the
power supply and microprocessor to stablize before RESET
is released.
~
~
tRPU
VCCTP (MIN)
~
~
VOH
VCCTP
VCCTP (MAX)
tR
VCC
RESET
Figure 1: Timing Diagram: Power-Up
~
~
VCCTP (MIN)
VCCTP
VCCTP (MAX)
tF
VCC
tRPD
VOL
RESET
Figure 2: Timing Diagram: Power-Down
ASM1233A
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Notice: The information in this document is subject to change without notice
Low Power, 3.3V, µP Reset, Active LOW, Open-Drain Output
rev 1.0
November 2003
Absolute Maximum Ratings
Parameter Min Max Unit
Voltage on VCC -0.5 7 V
Voltage on RESET -0.5 VCC + 0.5 V
Operating Temperature Range -40 85 °C
Soldering Temperature (for 10 sec) 260 °C
Storage Temperature -55 125 °C
NOTE: These are stress ratings only and functional use is not implied. Exposure to absolute maximum rat-
ings for prolonged periods of time may affect device reliability.
ASM1233A
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Notice: The information in this document is subject to change without notice
Low Power, 3.3V, µP Reset, Active LOW, Open-Drain Output
rev 1.0
November 2003
Electrical Characteristics
Unless otherwise noted, VCC = 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 Symbol Conditions Min Typ Max Unit
Supply Voltage VCC 1.2 5.5 V
Output Voltage VOH IOUT < 500 µA VCC - 0.5V VCC - 0.1V V
Output Current IOL Output = 0.4V, VCC >= 2.7V +8 mA
Operating Current ICC
VCC < =3.6V, RESET output
open 615µA
VCC Trip Point (ASM1233A-3) VCCTP 2.64 2.72 2.8 V
Voltage High Trip Level
ASM1233A-3 VHTL 3.14 V
Internal Pull-up Resistor RP3.5 5.0 7.5 kΩ
Output Capacitance COUT 10 pF
VCC Detect to RESET Low tRPD 210µs
VCC Slew Rate
(VHTL - VLTL ) tF300 µs
VCC Slew Rate
(VLTL - VHTL)tR0ns
VCC Detect to RESET High tRPU tr = 5µs 200 350 500 ms
Note: A 1kΩ resistor maybe required in some applications for proper operation of the microprocessor reset control circuit.
ASM1233A
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Notice: The information in this document is subject to change without notice
Low Power, 3.3V, µP Reset, Active LOW, Open-Drain Output
rev 1.0
November 2003
Family Selection Guide
Part # RESET Voltage (V) RESET Time
(ms) Output Stage RESET Polarity
ASM1810 4.620, 4.370, 4.120 150 Push-Pull LOW
ASM1811 4.620, 4.350, 4.130 150 Open-Drain LOW
ASM1812 4.620, 4.350, 4.130 150 Push-Pull HIGH
ASM1815 3.060, 2.880, 2.550 150 Push-Pull LOW
ASM1816 3.060, 2.880, 2.550 150 Open-Drain LOW
ASM1817 3.060, 2.880, 2.550 150 Push-Pull HIGH
ASM1233D 4.625, 4.375, 4.125 350 Open-Drain LOW
ASM1233M 4.625, 4.375, 2.720 350 Open-Drain LOW
ASM1233A 2.720 350 Open-Drain LOW
ASM1233A
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Notice: The information in this document is subject to change without notice
Low Power, 3.3V, µP Reset, Active LOW, Open-Drain Output
rev 1.0
November 2003
Package Information
SOT-223
Symbol
Dimensions in millimeters Dimensions in Inches
Min Max Min Max
A 0.067 0.060 1.70 1.50
A1 0.004 0.0008 0.10 0.02
B 0.124 0.116 3.15 2.95
B1 0.033 0.026 0.85 0.65
C 0.014 0.010 0.35 0.25
D 0.264 0.248 6.70 6.30
e 0.0905 NOM 2.30 NOM
e1 0.181 NOM 4.50 NOM
E 0.146 0.130 3.70 3.30
h 0.287 0.264 7.30 6.70
s 0.041 0.033 1.05 0.85
Q 10 ° MAX 10 ° MAX
Q1 16° 10° 16° 10°
Q2 16° 10° 16° 10°
B
EH
Se
D
A
A1
e1
B1
Q
Q1
Q2
C
ASM1233A
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Notice: The information in this document is subject to change without notice
Low Power, 3.3V, µP Reset, Active LOW, Open-Drain Output
rev 1.0
November 2003
Ordering Information
Part Number RESET Output Voltage RESET Tolerance RESET Time Open-Drain
Output Stage* RESET Polarity
ASM1233AZ-15 2.720 V 15% 350 ms LOW
* Internal 5kΩ resistor pull-up
Alliance Semiconductor Corporation
2575, Augustine Drive,
Santa Clara, CA 95054
Tel: 408 - 855 - 4900
Fax: 408 - 855 - 4999
www.alsc.com
Copyright © Alliance Semiconductor
All Rights Reserved
Preliminary Information
Part Number: ASM1233A
Document Version: 1.0
© Copyright 2003 Alliance Semiconductor Corporation. All rights reserved. Our three-point logo, our name and Intelliwatt are trademarks or
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ASM1233A
