ASM1834A/D
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 Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset
October 2003
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 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.
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.
Key Features
• Monitor 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
+5V 3.3V
5VIN
RESET
PBRST
5VTOL GND
3.3VTOL
3.3VIN
RESET
GND
µP
3.3V 5V
ASM1834
ASM1834A/D
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Notice: The information in this document is subject to change without notice
Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset
rev 1.0
October 2003
Block Diagram
Pin Configuration
Pin Description
Pin # Pin Name Function
15VIN 5V power supply input.
25V RESET
5V RESET
5V reset output (Active LOW, ASM1834, ASM1834A. Open drain outputs for ASM1834A).
5V reset output (Active HIGH, AS1834D).
35V TOL
5V input tolerance select: 10% tolerance for 5VTOL= 5VIN and 5% tolerance for 5VTOL = GND
4 GND Ground.
5 PBRST Debounced manual pushbutton reset input (40kΩ internal pull-up).
63.3V TOL
3.3V input tolerance select: 20% tolerance for 3.3VTOL = 3.3VIN and 10% tolerance for 3.3VTOL=GND.
73.3V RESET
3.3V RESET
3.3V reset output (Active LOW, ASM1834, ASM1834A. Open drain outputs for ASM1834A).
3.3V reset output (Active HIGH, AS1834D).
83.3VIN 3.3V power supply input.
1
2
3
45
6
7
8
5VIN
5V RESET *
5V TOL
GND
3.3VIN
3.3V RESET *
PBRST
3.3V TOL
ASM1834
ASM1834A
ASM1834D
* AS1834D reset outputs are active HIGH (5V RESET and 3.3V RESET)
Outputs are open-drain for AS1834A.
5V Tolerance
Bias
Low TC
3.3V Tolerance
Pushbutton Level
For ASM1834D
350ms Delay
5 V
IN
5 VTOL
PBRST
3.3 V
IN
3.3 VTOL
GND
3.3V RESET
3.3V RESET (ASM1834D)
5V RESET
5V RESET
ASM1834
350ms Delay
Reference
Bias
Sense and Debounce
For ASM1834D
-
+
-
ASM1834A
5V RESET
3.3V RESET
40k
Ω
(ASM1834D)
+
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Notice: The information in this document is subject to change without notice
Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset
ASM1834A/D
rev 1.0
October 2003
Detailed Description
Operation Power Monitor
The ASM1834 supervisors simultaneously detect out-of-
tolerance power supply conditions on both 3.3V and 5V
power supplies. If the voltages at 5VIN or 3.3VIN are outside
the tolerance band, the reset for the falling supply voltage
becomes active. When the monitored supply returns to an in-
tolerance state, the reset remains active for approximately
350ms before returning to the inactive state.
On power-up, the reset signals are kept active for
approximately 350ms after the power supply voltages have
reached the selected tolerance. This allows the power supply
and microprocessor to stabilize before the reset is removed.
All supply current for the ASM1834 devices is drawn from the
input (5VIN or 3.3VIN) with the highest voltage level. The
outputs draw current from their input supplies 5VIN and
3.3VIN.
Reset Signal Polarity and Output Stage Structure
The ASM1834 and the ASM1834A supervisors have active
LOW reset signals. The ASM1834D reset outputs are active
HIGH.
The ASM1834 and the ASM1834D have CMOS push-pull
output satges. The ASM1834A has open drain reset outputs.
Part # RESET
Polarity
Output Stage
Configuration
ASM1834 LOW Push-Pull
ASM1834EMA LOW Push-Pull
ASM1834S LOW Push-Pull
ASM1834A LOW Open Drain
ASM1834AEMA LOW Open Drain
ASM1834AS LOW Open Drain
ASM1834D HIGH Push-Pull
ASM1834DEMA HIGH Push-Pull
ASM1834DS HIGH Push-Pull
~
~
~
~
~
~
V
OH
V
OL
t
RPU
RESET
RESET
V
INTP
(MIN)
V
INTP
(MAX)
V
INTP
t
R
V
IN
Figure 1: Timing Diagram : Power Up
~
~
~
~
~
~
V
OH
V
OL
V
INTP
(MAX)
V
INTP
V
INTP
(MIN)
RESET
RESET
t
F
V
IN
t
RPD
Figure 2: Timing Diagram : Power Down
RESET Slews
withV
CC
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Notice: The information in this document is subject to change without notice
Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset
ASM1834A/D
rev 1.0
October 2003
Manual Reset Operation
Push-button switch input, PBRST, allows the user to override
the internal trip point detection circuits and issue reset
signals. The pushbutton input is debounced and is pulled
HIGH through an internal 40kΩ resistor.
When at least one of the reset outputs is not asserted, a push
button initiated reset signal can be issued by holding PBRST
LOW for at least 2ms. When PBRST is held LOW, both resets
become active and remain active for approximately 350ms
after PBRST returns HIGH. (See figures 3 and 4).
Reset Output Signal
Reset output signals are valid as long as either voltage at
5VIN or 3.3VIN is above 1.2V. In addition, the ASM1834 has
push-pull outputs that can remain valid below a 1.2V input
level. To sink current below 1.2V, a resistor should be
connected from the reset output to ground. This resistor
guarantees a valid reset signal down to 0V. A 100kΩ value is
suggested.
The AS1834A open drain reset outputs require pull-up
resistors and must be low enough in value to pull the output
into a HIGH state. Resistor value is not critical in most
applications and a value of 10kΩ is suggested. (See Figures
5 and 6).
The ASM1834A open drain reset outputs can be connected
to the same potential through a single pull-up resistor. In this
configuration a failure on either supply will generate an active
LOW reset. If the inputs are pulled-up to different voltages,
the reset outputs (pin 2 and pin 7) cannot be connected to
form a wired “AND”(see figure 7).
~
~~
~~
~
V
OH
V
OL
RESET
RESET
PBRST t
PB
t
PDLY
V
IH
t
RST
Figure 4: Timing Diagram: Pushbutton Reset
1
2
3
45
6
7
8
3.3V
5V
3.3VIN
3.3V RESET
5VTOL
GND PBRST
5VIN
5V RESET
3.3VTOL
ASM1834
Figure 3: Pushbutton Reset RESET
µP
Input
100kΩ
Figure 5: ASM1834 RESET Valid to 0V
1
2
3
45
6
7
8
3.3V
5V
3.3VIN
3.3V RESET
5VTOL
GND PBRST
5VIN
5V RESET
3.3VTOL
ASM1834
Figure 6: ASM1834A Open Drain Output Pull-Up Resistor
10kΩ10kΩ
V
IL
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Notice: The information in this document is subject to change without notice
Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset
ASM1834A/D
rev 1.0
October 2003
Trip Point Tolerance Selection
The 3.3VTOL and 5VTOL inputs allow independent sel;ection of
the reset trip points. If 5VTOL is connected to the 5V supply
input, a 10% tolerance is selected. If 5VTOL is grounded, a 5%
tolerance is selected.
If 3.3VTOL is connected to the 3.3V supply input, a 20%
tolerance is selected. If 3.3VTOL is grounded, a 10% tolerance
is selected. (Refer table below). The 3.3VTOL and 5VTOL
tolerance select inputs should be tied to the ground or to the
respective input supply voltage pin, 3.3VIN or 5VIN.
Tolerance Select
3.3V Input 5V Input
3.3V
Tolerance
TRIP Point (V) 5V
Tolerance
TRIP Point (V)
MIN NOM MAX MIN NOM MAX
5VTOL = 5VIN - - - - 10% 4.25 4.38 4.49
5VTOL = GND - - - - 5% 4.5 4.63 4.75
3.3VTOL = 3.3VIN 20% 2.47 2.55 2.64 - - - -
3.3VTOL = GND 10% 2.80 2.88 2.97 - - - -
1
2
3
45
6
7
8
5VIN
5VRESET 3.3VRESET
5V or 3.3V
3.3VIN
5V TOL
GND
3.3V TOL
PBRST
3.3V
ASM1834A
5V
10kΩ
Figure 7: ASM1834A Wired “AND” Connection
ASM1834A/D
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Notice: The information in this document is subject to change without notice
Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset
rev 1.0
October 2003
Absolute Maximum Ratings
Recomended DC Operating Conditions
Recomended DC operating condition over the operating temperature range of -40°C to +85°C. All voltages are referenced to
ground.
Parameter Min Max Unit
Voltage on VCC -0.5 7 V
Voltage on 5V RESET -0.5 +5VIN + 0.5V V
Voltage on 3.3V RESET -0.5 +3.3VIN + 0.5V V
Voltage on PBRST and reset outputs -0.5
(+5VIN + 0.5V) or (+3.3VIN + 0.5V)
whichever is greater
Operating Temperature Range -40 +85 °C
Soldering Temperature (for 10 sec) - 260 °C
Storage Temperature -55 +125 °C
Note:
1. Voltages are measured with respect to ground
2. These are stress ratings only and functional implication is not implied. Exposure to absolute maximum
ratings for extended periods may affect device reliability.
Parameter Symbol Conditions Min Typ Max Unit
5V Supply Voltage 5VIN 1.2 5.5 V
3.3V Supply Voltage 3.3VIN 1.2 5.5
PBRST Input High Level VIH Both 3.3VIN and 5VIN >=2.7V 2VINMAX + 0.3 V
PBRST Input High Level VIH Both 3.3VIN and 5VIN <=2.7V VINMAX - 0.4 V
PBRST Input Low Level VIL -0.3 0.5 V
ASM1834A/D
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Notice: The information in this document is subject to change without notice
Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset
rev 1.0
October 2003
DC Electrical Characteristics
Unless otherwise noted, VIN = 1.2V to 53.5V and specifications are over the operating temperature range of -40°C to 85°C.
Recomended DC operating condition over the operating temperature range of -40°C to +85°C. All voltages are referenced to
ground.
Parameter Symbol Conditions Min Typ Max Unit
Output Current IOH
Output = 2.4V. Either 3.3VIN or 5.5VIN
>=2.7V
(ASM1834/1834D only)
350 µA
Output Current IOL
Output = 0.4V. Either 3.3VIN or 5.5VIN
>=2.7V
(ASM1834/1834D only)
10 mA
Output Voltage VOH VIN - 0.1V V
Input Leakage IIL -1.0 +1.0 µA
5V Operating Current ICC
3.3VIN and 5VIN<=5.5V, RESET out-
puts open. 16 30 µA
3.3V Operating Current ICC
3.3VIN and 5VIN<=3.6V, RESET out-
puts open. 12 25 µA
5V Trip Point VINTP 5VTOL = GND 4.50 4.63 4.75 V
5V Trip Point VINTP 5VTOL = 5VIN 4.25 4.38 4.49 V
3.3V Trip Point VINTP 3.3VTOL = GND 2.80 2.88 2.97 V
3.3V Trip Point VINTP 3.3VTOL = 3.3VIN 2.47 2.55 2.64 V
Output Capacitance COUT 10 pF
PBRST Manual Reset
Minimum Low Time tPB 2ms
PBRST Stable LOW to
reset Active tPDLY 2ms
Reset Active Time tRST 200 350 500 ms
VCC Slew Rate tFVINTP(MAX) to VINTP(MIN) 300 µs
VCC Slew Rate tRVINTP(MIN) to VINTP(MAX) 0ns
VCC Detect to RESET
or RESET tRPU trise = 5µs 200 350 500 ms
VCC Detect Noise
Immunity tRPD 2µs
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Notice: The information in this document is subject to change without notice
Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset
ASM1834A/D
rev 1.0
October 2003
Package Information
MicroSO (8-Pin)
SO (8-Pin)
Plastic DIP (8-Pin)
Inches Millimeteres
Min Max Min Max
MicroSO (8-Pin)
A - 0.0433 - 0.10
A1 0.0020 0.0059 0.050 0.15
A2 0.0295 0.0374 0.75 0.95
b 0.0098 0.0157 0.25 0.40
C 0.0051 0.0091 0.13 0.23
D 0.1142 0.1220 2.90 3.10
e 0.0256 BSC 0.65 BSC
E 0.193 BSC 4.90 BSC
E1 0.1142 0.1220 2.90 3.10
L 0.0157 0.0276 0.40 0.70
a0°6°0°6°
SO (8-Pin)
A 0.053 0.069 1.35 1.75
A1 0.004 0.010 0.10 0.25
B 0.013 0.020 0.33 0.51
C 0.007 0.010 0.19 0.25
e 0.050 1.27
E 0.150 0.157 3.80 4.00
H 0.228 0.244 5.80 6.20
L 0.016 0.050 0.40 1.27
D 0.189 0.197 4.80 2.00
Plastic DIP (8-Pin)
A - 0.210 - 5.33
A1 0.015 - 0.38 -
A2 0.115 0.195 2.92 4.95
b 0.014 0.022 0.36 0.56
b2 0.045 0.070 1.14 1.78
b3 0.030 0.045 0.80 1.14
D 0.355 0.400 9.02 10.16
D1 0.005 - 0.13 -
E 0.300 0.325 7.62 8.26
E1 0.240 0.280 6.10 7.11
e 0.100 - 2.54
eA 0.300 - 7.62
eB - 0.430 - 10.92
eC - 0.060
L 0.115 0.150 2.92 3.81
E1 E
D
A
A1
A2
eb
C
L
a
0.10mm
0.004in
L
C
A
A1
EH
D
D
D1
A
A1
A2
L
b
b2
E
E1
C
eA
eB
0° - 15°
ASM1834A/D
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Notice: The information in this document is subject to change without notice
Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset
rev 1.0
October 2003
Ordering Information
Part Number Reset Polarity Operating Temperature
Range Output Stage Package
ASM1834 LOW -40°C TO 85°C Push-Pull 8-DIP
ASM1834EMA LOW -40°C TO 85°C Push-Pull MicroSO
ASM1834S LOW -40°C TO 85°C Push-Pull 8-SO
ASM1834/D LOW 25°C Push-Pull DICE
ASM1834A LOW -40°C TO 85°C Open Drain 8-DIP
AS1834AEMA LOW -40°C TO 85°C Open Drain MicroSO
ASM1834AS LOW -40°C TO 85°C Open Drain 8-SO
ASM1834A/D LOW 25°C Open Drain DICE
ASM1834D HIGH -40°C TO 85°C Push-Pull 8-DIP
ASM1834DEMA HIGH -40°C TO 85°C Push-Pull MicroSO
ASM1834DS HIGH -40°C TO 85°C Push-Pull 8-SO
ASM1834D/D HIGH 25°C Push-Pull DICE
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
Part Number: ASM1834A/D
Document Version: 1.0
© Copyright 2003 Alliance Semiconductor Corporation. All rights reserved. Our three-point logo, our name and Intelliwatt are trademarks or
registered trademarks of Alliance. All other brand and product names may be the trademarks of their respective companies. Alliance reserves the
right to make changes to this document and its products at any time without notice. Alliance assumes no responsibility for any errors that may
appear in this document. The data contained herein represents Alliance's best data and/or estimates at the time of issuance. Alliance reserves the
right to change or correct this data at any time, without notice. If the product described herein is under development, significant changes to these
specifications are possible. The information in this product data sheet is intended to be general descriptive information for potential customers and
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ASM1834A/D
