October 2003
rev 1.0
ASM809, ASM810
3 Pin Microcontroller Power Supply Supervisor
General Description
The ASM809/ASM810 are cost effective 3.0V, 3.3V and 5.0V
power supply supervisor circuits optimized for low-power
microprocessor (µP), microcontroller (µC) and digital systems.
They provide a reset output during power-up, power-down and
brown-out conditions. They provide excellent reliability by
eliminating
external
components
and
adjustments.
The
ASM809/810 are improved drop-in replacements for the Maxim
MAX809/810 and feature 60% lower supply current.
A reset signal is issued if the power supply voltage drops below
a preset reset threshold and is asserted for at least 140ms after
the supply has risen above the reset threshold. The ASM809
has an active-low RESET output that is guaranteed to be in the
correct logic state for V
CC
down to 1.1V. The ASM810 has an
active-high RESET output. The reset comparator is designed to
ignore fast transients on V
CC
.
Low supply current makes the ASM809/ASM810 ideal for use
in
portable
and
battery
operated
equipment.
The
ASM809/ASM810 are available in a compact, industry standard
3-pin SOT23 package.
Six voltage thresholds are available to support 3V to 5V
systems:
RESET THRESHOLD
Suffix
L
M
J
T
S
R
Voltage
4.63
4.38
4.00
3.08
2.93
2.63
Features:
•
•
•
•
•
•
Monitor 5V, 3.3V and 3V supplies
140ms min. reset pulse width
Active-low reset valid with 1.1V supply (ASM809)
Small 3-pin SOT-23 package
No external components
Specified over full temperature range - -40°C to 105°C
Applications
•
•
•
•
•
•
Embedded controllers
Portable/Battery operated systems
Intelligent instruments
Wireless communication systems
PDAs and handheld equipment
Computers
Typical Operating Circuit
V
CC
V
CC
V
CC
µP
RESET
(RESET)
GND
RESET (RESET)
Input
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
October 2003
rev 1.0
ASM809, ASM810
Block Diagram
SOT23
GND
1
Pin Diagram
V
CC
ASM809
(ASM810)
3
V
CC
+
-
+
-
RESET Generator
4.63V
4.38V
4.00V
3.08V
2.93V
2.63V
RESET
(RESET)
(RESET) RESET
2
ASM809
(ASM810)
GND
Pin Description
Pin #
ASM809
1
2
ASM810
-
-
Pin
Name
GND
RESET
Ground.
RESET is asserted LOW if V
CC
falls below V
TH
and remains LOW for T
RST
after V
CC
exceeds the
threshold.
RESET is asserted HIGH if V
CC
falls below V
TH
and remains HIGH for T
RST
after V
CC
exceeds the
threshold.
Power supply input voltage (3.0V, 3.3V, 5.0V).
Function
-
3
2
-
RESET
V
CC
Detailed Description
A
proper
reset
input
enables
a
microprocessor
/
V
CC
5V
0V
V
TH
microcontroller to start in a known state. ASM809/810 assert
reset to prevent code execution errors during power-up,
power-down and brown-out conditions.
RESET
Reset Timing
The reset signal is asserted- LOW for the ASM809 and HIGH
for the ASM810- when the V
CC
supply voltage falls below the
threshold trip voltage and remains asserted for 140ms
minimum after the V
CC
has risen above the threshold.
RESET
5V
0V
5V
0V
T
RST
ASM809
ASM810
Figure 1: Reset TIming Diagram
3 Pin Microcontroller Power Supply Supervisor
Notice: The information in this document is subject to change without notice
2 of 10
October 2003
rev 1.0
ASM809, ASM810
Bidirectional Reset Pin Interfacing
The ASM809/810 can interface with µP / µC bi-directional
reset pins by connecting a 4.7kΩ resistor in series with the
ASM809/810 reset output and the µP/µC bi-directional reset
pin.
Application Information
Negative V
CC
Transients
The ASM809/810 protect µPs from brownouts and low V
CC
.
Short duration transients of 100mV amplitude and 20µs or
less duration typically do not cause a false RESET.
Valid Reset with V
CC
under 1.1V
When V
CC
is under 1.1V, to ensure logic inputs connected to
the ASM809 RESET pin are in a known state, a 100kΩ pull-
down resistor is needed at RESET . The value of the resistor
is not critical. A 100kΩ pull-up resistor to V
CC
at RESET is
needed with the ASM810.
BUF
Buffered
RESET
V
CC
Power supply
ASM809
4.7kΩ
RESET
µC or µP
RESET
Input
GND
V
CC
GND
Power Supply
ASM809
RESET
GND
100kΩ
Bi-directional I/O Pin
Figure 4: Bidirectional Reset Pin Interfacing
Figure 2: RESET valid with V
CC
under 1.1V
V
CC
100kΩ
Power Supply
ASM810
RESET
GND
Figure 3: RESET valid with V
CC
under 1.1V
3 Pin Microcontroller Power Supply Supervisor
Notice: The information in this document is subject to change without notice
3 of 10
October 2003
rev 1.0
ASM809, ASM810
Absolute Maximum Ratings Table 1:
Parameter
Pin Terminal Voltage With Respect To Ground
V
CC
RESET, RESET
Input current at V
CC
Output current: RESET, RESET
Rate of Rise at V
CC
Min
Max
Units
-0.3
-0.3
6.0
V
CC
+ 0.3
20
20
100
V
V
mA
mA
V/µs
Note: These are stress ratings only and the functional operation is not implied. Exposure
to absolute maximum ratings for prolonged time periods may affect device reliability.
Absolute Maximum Ratings Table 2:
Parameter
Power Dissipation (T
A
= 70°C)
Operating temperature range
Storage temperature range
Lead temperature (Soldering, 10 sec)
Min
Max
320
Units
uW
°C
°C
°C
-40
-65
105
160
300
Note: These are stress ratings only and the functional operation is not implied. Exposure to absolute
maximum ratings for prolonged time periods may affect device reliability.
3 Pin Microcontroller Power Supply Supervisor
Notice: The information in this document is subject to change without notice
4 of 10
October 2003
rev 1.0
ASM809, ASM810
Electrical Characteristics:
Unless otherwise noted, V
CC
is over the full voltage range, T
A
= -40°C to 105°C.
Typical values at T
A
= 25°C, V
CC
= 5V for L/M/J devices, V
CC
= 3.3V for T/S devices and V
CC
= 3V for R devices.
Symbol
V
CC
Parameter
Input Voltage
Range
T
A
= 0°C to 70°C
Conditions
Min
1.1
1.2
Typ
Max
5.5
5.5
Unit
V
V
T
A
= -40°C to 105°C
T
A
= -40°C to 85°C
V
CC
< 5.5V, L/M/J
V
CC
< 3.6V, R/S/T
V
CC
< 5.5V, L/M/J
V
CC
< 3.6V, R/S/T
T
A
= 25°C
L devices
T
A
= -40°C to 85°C
T
A
= 85°C to 105°C
T
A
= 25°C
M devices
T
A
= -40°C to 85°C
T
A
= 85°C to 105°C
T
A
= 25°C
J devices
T
A
= -40°C to 85°C
T
A
= 85°C to 105°C
T
A
= 25°C
T devices
T
A
= -40°C to 85°C
T
A
= 85°C to 105°C
T
A
= 25°C
S devices
T
A
= -40°C to 85°C
T
A
= 85°C to 105°C
T
A
= 25°C
R devices
T
A
= -40°C to 85°C
T
A
= 85°C to 105°C
T
A
= -40°C to 85°C
T
A
= 85°C to 105°C
T
A
= 85°C to 105°C
I
CC
Supply Current
9
6.8
15
10
25
20
4.70
4.75
4.86
4.45
4.50
4.56
4.06
4.10
4.20
µA
4.56
4.50
4.40
4.31
4.25
4.16
3.93
3.89
3.80
3.04
3.00
2.92
2.89
2.85
2.78
2.59
2.55
2.50
4.63
4.38
4.00
V
TH
Reset Threshold
V
3.08
3.11
3.15
3.23
2.96
3.00
3.08
2.66
2.70
2.76
ppm/°C
µs
2.93
2.63
Reset Threshold
Temp Coefficient
V
CC
to Reset
Delay
V
CC
= V
TH
to V
TH
-100mV
30
60
Notes:
1. Production testing done at T
A
= 25°C. Over-temperature specifications guaranteed by design only, using six sigma design limits.
2. RESET output is active LOW for the ASM809 and RESET output is active HIGH for the ASM810.
3 Pin Microcontroller Power Supply Supervisor
Notice: The information in this document is subject to change without notice
5 of 10
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