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April 2005  
ASM1834/A/D  
rev 1.3  
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.  
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  
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.  
•
• ASM1834A  
• Active LOW  
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.  
•
•
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.  
All devices can generate reset signals through an internally  
debounced pushbutton reset input that affects both reset  
outputs.  
Wide operating temperature, -40°C to +85°C  
Applications  
Typical Operating Circuit  
•
•
•
•
•
•
•
Microprocessors  
PDAs, Hand-held PCs  
Embedded Controllers  
Telecommunication Systems  
Power Supplies  
3.3V  
+5V  
5V  
3.3V  
ASM1834  
µP  
Wireless / Cellular Systems  
Networking Hardware  
5V  
3.3V  
IN  
IN  
RESET  
RESET  
PBRST  
GND  
GND  
5VTOL  
3.3VTOL  
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  
April 2005  
ASM1834/A/D  
rev 1.3  
Block Diagram  
ASM1834A  
1
ASM1834  
5 VIN  
2
5V RESET  
3
5V Tolerance  
Bias  
+
For ASM1834D  
5 VTOL  
5V RESET  
2
350ms Delay  
5V RESET  
(ASM1834D)  
Low TC  
-
7
3.3V RESET  
Reference  
40kΩ  
5
Pushbutton Level  
PBRST  
Sense and Debounce  
8
3.3 VIN  
6
For ASM1834D  
3.3 VTOL  
3.3V Tolerance  
Bias  
+
3.3V RESET  
7
350ms Delay  
3.3V RESET (ASM1834D)  
4
GND  
-
Pin Configuration  
1
8
7
6
5
3.3VIN  
5VIN  
ASM1834  
ASM1834A  
ASM1834D  
2
3
3.3V RESET *  
5V RESET *  
5V TOL  
3.3V TOL  
PBRST  
4
GND  
* AS1834D reset outputs are active HIGH (5V RESET and 3.3V RESET)  
Outputs are open-drain for AS1834A.  
Pin Description  
Pin #  
Pin Name  
Function  
5VIN  
1
5V power supply input.  
5V RESET  
5V RESET  
5V reset output (Active LOW, ASM1834, ASM1834A. Open drain outputs for ASM1834A).  
5V reset output (Active HIGH, AS1834D).  
2
5V input tolerance select: 10% tolerance for 5VTOL= 5VIN and 5% tolerance for 5VTOL = GND  
3
4
5
6
5V TOL  
GND  
Ground.  
PBRST  
3.3V TOL  
Debounced manual pushbutton reset input (40kΩ internal pull-up).  
3.3V input tolerance select: 20% tolerance for 3.3VTOL = 3.3VIN and 10% tolerance for 3.3VTOL=GND.  
3.3V RESET 3.3V reset output (Active LOW, ASM1834, ASM1834A. Open drain outputs for ASM1834A).  
3.3V RESET 3.3V reset output (Active HIGH, AS1834D).  
7
8
3.3VIN  
3.3V power supply input.  
2 of 10  
Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset  
Notice: The information in this document is subject to change without notice  
April 2005  
ASM1834/A/D  
rev 1.3  
Detailed Description  
t
F
V
IN  
Operation Power Monitor  
V
(MAX)  
V
INTP  
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.  
INTP  
V
(MIN)  
INTP  
RESET  
t
RPD  
RESET Slews  
with V  
V
CC  
OH  
V
OL  
RESET  
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.  
Figure 2: Timing Diagram: Power Down (ASM1834D only)  
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.  
All supply current for the ASM1834 devices is drawn from the  
input (5VIN or 3.3VIN) with the highest voltage level. The  
The ASM1834 and the ASM1834D have CMOS push-pull  
output stages. The ASM1834A has open drain reset outputs.  
outputs draw current from their input supplies 5VIN and  
3.3VIN.  
t
R
RESET  
Polarity  
Output Stage  
Configuration  
Part #  
V
(MAX)  
INTP  
V
INTP  
V
(MIN)  
INTP  
ASM1834  
ASM1834U  
ASM1834S  
ASM1834A  
ASM1834AU  
ASM1834AS  
ASM1834D  
ASM1834DU  
ASM1834DS  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
HIGH  
HIGH  
HIGH  
Push-Pull  
Push-Pull  
Push-Pull  
Open Drain  
Open Drain  
Open Drain  
Push-Pull  
Push-Pull  
Push-Pull  
t
RPU  
V
IN  
RESET  
RESET  
V
OH  
V
OL  
Figure 1: Timing Diagram: Power Up (ASM1834D only)  
3 of 10  
Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset  
Notice: The information in this document is subject to change without notice  
April 2005  
ASM1834/A/D  
rev 1.3  
Manual Reset Operation  
Reset Output Signal  
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.  
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.  
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).  
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).  
3.3V  
5V  
ASM1834  
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).  
8
1
3.3VIN  
5VIN  
7
6
5
2
5V RESET 3.3V RESET  
3
4
5VTOL  
GND  
3.3VTOL  
PBRST  
µP  
Input  
RESET  
Figure 3: Pushbutton Reset  
PBRST  
100kΩ  
t
PB  
Figure 5: ASM1834 RESET Valid to 0V  
V
IH  
t
PDLY  
V
IL  
3.3V  
5V  
t
ASM1834  
RST  
8
1
3.3VIN  
5VIN  
RESET  
RESET  
10kΩ  
VOH  
VOL  
10kΩ  
7
6
5
2
5V RESET 3.3V RESET  
3
4
5VTOL  
GND  
3.3VTOL  
PBRST  
Figure 4: Timing Diagram: Pushbutton Reset  
Figure 6: ASM1834A Open Drain Output Pull-Up Resistor  
4 of 10  
Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset  
Notice: The information in this document is subject to change without notice  
April 2005  
ASM1834/A/D  
rev 1.3  
5V  
5V or 3.3V  
3.3V  
10kΩ  
ASM1834A  
8
7
6
1
2
3
5V  
IN  
3.3V  
IN  
3.3VRESET  
3.3V TOL  
PBRST  
5VRESET  
5V TOL  
GND  
4
5
Figure 7: ASM1834A Wired “OR” Connection  
Trip Point Tolerance Selection  
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.  
The 3.3VTOL and 5VTOL inputs allow independent selection 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.  
3.3V Input  
5V Input  
Tolerance Select  
TRIP Point (V)  
TRIP Point (V)  
5V  
3.3V  
Tolerance  
Tolerance  
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%  
10%  
2.47  
2.80  
2.55  
2.88  
2.64  
2.97  
-
-
-
-
-
-
-
-
3.3VTOL = GND  
5 of 10  
Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset  
Notice: The information in this document is subject to change without notice  
April 2005  
ASM1834/A/D  
rev 1.3  
Absolute Maximum Ratings  
Parameter  
Voltage on VCC  
Min  
-0.5  
-0.5  
-0.5  
Max  
Unit  
V
7
+5VIN + 0.5V  
Voltage on 5V RESET  
Voltage on 3.3V RESET  
V
+3.3VIN + 0.5V  
V
(+5VIN + 0.5V) or (+3.3VIN + 0.5V)  
whichever is greater  
Voltage on PBRST and reset outputs  
-0.5  
V
Operating Temperature Range  
Soldering Temperature (for 10 sec)  
Storage Temperature  
-40  
-
+85  
260  
°C  
°C  
°C  
-55  
+125  
ESD rating  
HBM  
2
200  
KV  
V
MM  
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.  
Recommended DC Operating Conditions  
Recommended DC operating condition over the operating temperature range of -40°C to +85°C. All voltages are referenced to  
ground.  
Parameter  
Symbol  
5VIN  
3.3VIN  
VIH  
Conditions  
Min  
1.2  
1.2  
2
Typ  
Max  
Unit  
V
5V Supply Voltage  
5.5  
5.5  
3.3V Supply Voltage  
PBRST Input High Level  
PBRST Input High Level  
PBRST Input Low Level  
V
Both 3.3VIN and 5VIN >=2.7V  
VINMAX + 0.3  
V
VIH  
Both 3.3VIN and 5VIN <=2.7V VINMAX - 0.4  
-0.3  
V
VIL  
0.5  
V
6 of 10  
Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset  
Notice: The information in this document is subject to change without notice  
April 2005  
ASM1834/A/D  
rev 1.3  
DC Electrical Characteristics  
Unless otherwise noted, VIN = 1.2V to 5.5V and specifications are over the operating temperature range of -40°C to 85°C.  
Parameter  
Symbol  
Conditions  
Min  
Typ  
Max  
Unit  
Output = 2.4V. Either 3.3VIN or 5.5VIN  
IOH  
Output Current  
350  
µA  
>=2.7V  
(ASM1834/1834D only)  
Output = 0.4V. Either 3.3VIN or 5.5VIN  
IOL  
Output Current  
10  
mA  
>=2.7V  
(ASM1834/1834D only)  
VOH  
IIL  
ICC  
VIN - 0.1V  
Output Voltage  
Input Leakage  
V
-1.0  
+1.0  
30  
µA  
3.3VIN and 5VIN<=5.5V, RESET  
outputs open.  
5V Operating Current  
3.3V Operating Current  
16  
12  
µA  
µA  
3.3VIN and 5VIN<=3.6V, RESET  
outputs open.  
ICC  
25  
VINTP  
VINTP  
VINTP  
VINTP  
COUT  
5V Trip Point  
5VTOL = GND  
5VTOL = 5VIN  
4.50  
4.25  
2.80  
2.47  
4.63  
4.38  
2.88  
2.55  
4.75  
4.49  
2.97  
2.64  
10  
V
V
5V Trip Point  
3.3V Trip Point  
3.3V Trip Point  
Output Capacitance  
3.3VTOL = GND  
3.3VTOL = 3.3VIN  
V
V
pF  
PBRST Manual Reset  
Minimum Low Time  
tPB  
2
ms  
ms  
PBRST Stable LOW to  
reset Active  
tPDLY  
2
tRST  
tF  
Reset Active Time  
VCC Slew Rate  
200  
300  
0
350  
350  
500  
ms  
µs  
ns  
VINTP(MAX) to VINTP(MIN)  
VINTP(MIN) to VINTP(MAX)  
VCC Slew Rate  
tR  
VCC Detect to RESET  
or RESET  
tRPU  
trise = 5µs  
200  
500  
2
ms  
µs  
VCC Detect Noise  
Immunity  
tRPD  
7 of 10  
Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset  
Notice: The information in this document is subject to change without notice  
April 2005  
ASM1834/A/D  
rev 1.3  
Package Information  
MicroSO (8-Pin)  
Dimensions  
Symbol  
Inches  
Millimeters  
Min  
Max  
0.044  
0.006  
0.038  
Min  
Max  
1.10  
0.15  
0.97  
A
A1  
A2  
b
C
D
0.032  
0.002  
0.030  
0.81  
0.05  
0.76  
0.012 BSC  
0.30 BSC  
0.65 BSC  
0.004  
0.114  
0.008  
0.122  
0.10  
2.90  
0.20  
3.10  
e
0.0256 BSC  
E1  
E
L
0.114  
0.184  
0.016  
0°  
0.122  
0.200  
0.026  
6°  
2.90  
4.67  
0.41  
0°  
3.10  
5.08  
0.66  
6°  
a
S
0.0206 BSC  
0.52 BSC  
Dimensions  
Symbol  
Inches  
Millimeters  
Min  
SO (8-PIN)  
Min  
Max  
Max  
0.25  
1.75  
1.50  
0.51  
0.25  
A1  
A
0.004  
0.053  
0.049  
0.012  
0.007  
0.010  
0.069  
0.059  
0.020  
0.010  
0.10  
1.35  
1.25  
0.31  
0.18  
A2  
B
H
E
C
D
E
0.193 BSC  
0.154 BSC  
0.050 BSC  
0.236 BSC  
4.90 BSC  
3.91 BSC  
1.27 BSC  
6.00 BSC  
D
e
H
L
A2  
A
0.016  
0.050  
8°  
0.41  
0°  
1.27  
8°  
C
θ
θ
0°  
e
A1  
L
B
Dimensions  
PLASTIC DIP (8-PIN)  
Symbol  
Inches  
Millimeters  
Min  
Max  
0.210  
…..  
Min  
…..  
Max  
5.33  
…..  
A
A1  
A2  
b
….  
0.015  
0.115  
0.014  
0.045  
0.008  
0.355  
0.300  
0.240  
0.38  
2.92  
0.36  
1.14  
0.20  
9.02  
7.62  
6.10  
0.195  
0.022  
0.070  
0.014  
0.400  
0.325  
0.280  
4.95  
0.56  
1.78  
0.36  
10.16  
8.26  
7.11  
b2  
C
D
E
E1  
e
0.10 BSC  
2.54 BSC  
eB  
L
…..  
0.115  
0.430  
0.150  
…..  
10.92  
3.81  
2.92  
8 of 10  
Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset  
Notice: The information in this document is subject to change without notice  
April 2005  
ASM1834/A/D  
rev 1.3  
Ordering Information  
Reset  
Polarity  
Operating  
Temperature Range  
Package  
Marking  
Part Number  
Output Stage  
Package  
TIN - LEAD DEVICES  
ASM1834  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
HIGH  
HIGH  
HIGH  
-40°C TO 85°C  
-40°C TO 85°C  
-40°C TO 85°C  
-40°C TO 85°C  
-40°C TO 85°C  
-40°C TO 85°C  
-40°C TO 85°C  
-40°C TO 85°C  
-40°C TO 85°C  
Push-Pull  
Push-Pull  
Push-Pull  
Open Drain  
Open Drain  
Open Drain  
Push-Pull  
Push-Pull  
Push-Pull  
8-DIP  
MicroSO  
8-SO  
ASM1834  
ASM1834U  
ASM1834S  
ASM1834A  
ASM1834AU  
ASM1834AS  
ASM1834D  
ASM1834DU  
ASM1834DS  
ASM1834U  
ASM1834S  
ASM1834A  
8-DIP  
ASM1834AU  
ASM1834AS  
ASM1834D  
MicroSO  
8-SO  
8-DIP  
ASM1834DU  
ASM1834DS  
LEAD FREE DEVICES  
ASM1834F  
MicroSO  
8-SO  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
HIGH  
HIGH  
HIGH  
-40°C TO 85°C  
-40°C TO 85°C  
-40°C TO 85°C  
-40°C TO 85°C  
-40°C TO 85°C  
-40°C TO 85°C  
-40°C TO 85°C  
-40°C TO 85°C  
-40°C TO 85°C  
Push-Pull  
Push-Pull  
Push-Pull  
Open Drain  
Open Drain  
Open Drain  
Push-Pull  
Push-Pull  
Push-Pull  
8-DIP  
MicroSO  
8-SO  
ASM1834F  
ASM1834UF  
ASM1834SF  
ASM1834AF  
ASM1834AUF  
ASM1834ASF  
ASM1834DF  
ASM1834DUF  
ASM1834DSF  
ASM1834UF  
ASM1834SF  
ASM1834AF  
ASM1834AUF  
ASM1834ASF  
ASM1834DF  
ASM1834DUF  
ASM1834DSF  
8-DIP  
MicroSO  
8-SO  
8-DIP  
MicroSO  
8-SO  
Note:  
For parts to be packed in Tape and Reel, add “-T” at the end of the part number.  
9 of 10  
Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset  
Notice: The information in this document is subject to change without notice  
ASM1834/A/D  
Copyright © Alliance Semiconductor  
All Rights Reserved  
Part Number: ASM1834/A/D  
Document Version: 1.3  
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 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  
users, and is not intended to operate as, or provide, any guarantee or warrantee to any user or customer. Alliance does not assume any responsibility  
or liability arising out of the application or use of any product described herein, and disclaims any express or implied warranties related to the sale  
and/or use of Alliance products including liability or warranties related to fitness for a particular purpose, merchantability, or infringement of any  
intellectual property rights, except as express agreed to in Alliance's Terms and Conditions of Sale (which are available from Alliance). All sales of  
Alliance products are made exclusively according to Alliance's Terms and Conditions of Sale. The purchase of products from Alliance does not  
convey a license under any patent rights, copyrights; mask works rights, trademarks, or any other intellectual property rights of Alliance or third  
parties. Alliance does not authorize its products for use as critical components in life-supporting systems where a malfunction or failure may  
reasonably be expected to result in significant injury to the user, and the inclusion of Alliance products in such life-supporting systems implies that  
the manufacturer assumes all risk of such use and agrees to indemnify Alliance against all claims arising from such use.