July 2005
rev 1.8
ASM809,ASM8091,ASM810
3-Pin Microcontroller Power Supply Supervisor
Six voltage thresholds are available to support 3V to 5V
systems:
General Description
The ASM809/ASM8091/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/ASM8091/ASM810
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/
ASM8091 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/ASM8091/ASM810
ideal for use in portable and battery operated equipment. The
ASM809/ASM8091/ASM810 are available in a compact,
industry standard 3&5-pin SOT-23 Packages.
RESET THRESHOLD
Suffix
L
M
J
T
S
R
Voltage (V)
4.63
4.38
4.00
3.08
2.93
2.63
Features:
•
•
•
•
•
•
Monitor 5V, 3.3V and 3V supplies
140mS minimum reset pulse width
Active-low reset valid with 1.1V supply (ASM809/
ASM8091)
Small 3&5-pin SOT-23 Packages
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 equipments
Computers
Typical Operating Circuit
V
CC
V
CC
ASM809
ASM8091
(ASM810)
RESET
(RESET)
GND
V
CC
µP
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
July 2005
rev 1.8
ASM809,ASM8091,ASM810
Pin Diagram
3-SOT23
GND
1
5-SOT23
1
Block Diagram
5
NC
RESET
ASM809
(ASM810)
3
V
CC
V
CC
+
-
+
-
RESET Generator
4.63V
4.38V
4.00V
3.08V
2.93V
2.63V
RESET
(RESET)
V
CC
2
ASM8091
(RESET) RESET
2
GND
3
4
NC
ASM809/8091
(ASM810)
GND
Pin Description
Pin #
ASM8091
5-SOT 23
3
1
ASM809
3-SOT 23
1
2
ASM810
-
-
Pin
Name
GND
RESET
Ground.
RESET is asserted LOW if V
CC
falls below V
TH
and remains LOW for
atleast 140mS (T
RST
) after V
CC
exceeds the threshold.
RESET is asserted HIGH if V
CC
falls below V
TH
and remains HIGH for
atleast 140mS (T
RST
) after V
CC
exceeds the threshold.
Power supply input voltage (3.0V, 3.3V, 5.0V).
Function
-
2
-
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/ASM8091/
ASM810 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,ASM8091
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
ASM8091
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 12
July 2005
rev 1.8
ASM809,ASM8091,ASM810
Application Information
Negative V
CC
Transients
The ASM809/ASM8091/ASM810 protect µpS from brownouts
and low V
CC
. Short duration transients of 100mV amplitude
and 60µpS 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,ASM8091 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.
Bidirectional Reset Pin Interfacing
The ASM809/ASM8091/ASM810 can interface with µP / µC
bi-directional reset pins by connecting a 4.7kΩ resistor in
series with the ASM809/ASM8091/ASM810 reset output and
the µP/µC bi-directional reset pin.
BUF
Buffered
RESET
V
CC
Power supply
ASM809
ASM8091
RESET
µC or µP
4.7kΩ
RESET
Input
GND
V
CC
GND
Power Supply
ASM809
ASM8091
Bi-directional I/O Pin
RESET
100kΩ
Figure 4: Bidirectional Reset Pin Interfacing
GND
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 12
July 2005
rev 1.8
ASM809,ASM8091,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
ESD rating
HBM
MM
Min
Max
Units
-0.3
-0.3
6.0
V
CC
+ 0.3
20
20
100
2
200
V
V
mA
mA
V/µs
KV
V
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
mW
°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 12
July 2005
rev 1.8
ASM809,ASM8091,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
T
A
= -40°C to 105°C
T
A
= -40°C to 85°C
Conditions
Min
1.1
1.2
Typ
Max
5.5
5.5
Unit
V
V
V
CC
< 5.5V
V
CC
< 3.6V
V
CC
< 5.5V
V
CC
< 3.6V
T
A
= 25°C
T
A
= -40°C to 85°C
T
A
= 85°C to 105°C
T
A
= 25°C
T
A
= -40°C to 85°C
T
A
= 85°C to 105°C
T
A
= 25°C
T
A
= -40°C to 85°C
T
A
= 85°C to 105°C
T
A
= 25°C
T
A
= -40°C to 85°C
T
A
= 85°C to 105°C
T
A
= 25°C
T
A
= -40°C to 85°C
T
A
= 85°C to 105°C
T
A
= 25°C
T
A
= -40°C to 85°C
T
A
= 85°C to 105°C
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
I
CC
Supply Current
T
A
= -40°C to 85°C
T
A
= 85°C to 105°C
T
A
= 85°C to 105°C
9
6.0
15
10
25
20
4.70
4.75
4.86
4.45
4.50
4.56
4.06
4.10
4.20
µA
L devices
4.63
M devices
4.38
J devices
V
TH
Reset Threshold
T devices
4.00
V
3.08
3.11
3.15
3.23
2.96
3.00
3.08
2.66
2.70
2.76
ppm/°C
µs
S devices
2.93
R devices
2.63
Reset Threshold
Temp Coefficient
V
CC
to Reset
Delay
V
CC
= V
TH
to V
TH
-100mV
30
20
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/ASM8091 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 12
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