February 2005
rev 1.4
ASM1815
Low Power, 3.3V/3.0V µP Reset Active LOW, Push-Pull Output
Applications
•
•
•
•
•
•
•
Set-top boxes
Cellular phones
PDAs
Energy management systems
Embedded control systems
Printers
Single board computers
General Description
The ASM1815 is a voltage supervisory device with low-power,
3.3V/3.0V µP Reset, active LOW, Push-Pull output. Maximum
supply current over temperature is a low 15µA (at 3.6V).
The ASM1815 generates an active LOW reset signal whenever
the monitored supply is out of tolerance. A precision reference
and comparator circuit monitor power supply (V
CC
)
level.
Tolerance level options are 5%, 10% and 20%. When an out-of-
tolerance condition is detected, an internal power-fail signal is
generated which forces an active LOW reset signal. After V
CC
returns to an in-tolerance condition, the reset signal remains
active for 150ms to allow the power supply and system
microprocessor to stabilize.
The ASM1815 is designed with a push-pull output stage and
operates over the extended industrial temperature range.
Devices are available in TO-92 and compact surface mount
SOT-23 packages.
Other low power products in this family include the ASM1810/
11/12/16/17, ASM1233D and ASM1233M.
Typical Operating Circuit
V
CC
ASM1815
Microprocessor
RESET
RESET
GND
Key Features
•
Low Supply Current
•20 µA maximum (5.5 V)
•15 µA maximum (3.6 V)
•
•
•
•
•
•
•
•
Automatically restarts a microprocessor after power failure
150ms reset delay after V
CC
returns to an in-tolerance con-
dition
Active LOW power-up reset
Precision temperature-compensated voltage reference and
comparator
Eliminates external components
TO-92 and compact surface mount SOT-23 package
Push-Pull output for minimum current drain
Operating temperature -40°C to +85°C
Block Diagram
V
CC
2
Supply
Tolerance
Bias
ASM1815
+
-
Reference
Delay
150ms
Typical
1
RESET
3
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
February 2005
rev 1.4
ASM1815
Pin Configuration
TO-92
SOT-23
RESET
1
ASM1815-R
ASM1815
3 GND
V
CC
2
1
2
3
Pin Description
TO-92
Pin #
1
2
3
SOT-23
Pin Name
Pin #
1
2
3
RESET
V
CC
GND
Active LOW reset output
Power supply input
Ground
Description
Low Power, 3.3V/3.0V µP Reset
Notice: The information in this document is subject to change without notice
2 of 9
February 2005
rev 1.4
ASM1815
V
CC
V
CCTP
(MAX)
t
F
Application Information
Operation - Power Monitor
The
ASM1815
detects
out-of-tolerance
power
supply
conditions. It resets a processor during power-up, power-
down and issues a reset to the system processor when the
When an out-of-tolerance V
CC
voltage is detected, the
RESET signal is asserted. On power-up, RESET is kept
active (LOW) for approximatley 150ms after the power supply
voltage has reached the selected tolerance. This allows the
power supply and microprocessor to stablize before RESET
is released.
t
R
V
CCTP
(MAX)
V
CCTP
(MIN)
V
CCTP
V
CCTP
V
CCTP
(MIN)
RESET
t
RPD
V
OL
Figure 2: Timing Diagram: Power-Down
Output Conditions
The ASM1815 active LOW reset signal is valid as long as
V
CC
remains below 1.2V. The RESET output on the
ASM1815 uses a push-pull drive stage that can maintain a
V
CC
t
RPU
valid output below 1.2V. To sink current with V
CC
below 1.2V,
a resistor can be connected from the reset pin (RESET) to
Ground (see Figure 3). This configuration will give a valid
value on the RESET output with V
CC
approaching 0V. During
both power up and down, this configuration will draw current
when the RESET is in the high state. A value of 100kΩ
should be adequate to maintain a valid connection.
V
OH
RESET
Figure 1: Timing Diagram: Power-Up
ASM1815
Microprocessor
RESET
100kΩ
RESET
Figure 3: RESET Valid to 0V V
CC
~
~
3 of 9
monitored power supply voltage is below the reset threshold.
~
~
~
~
Low Power, 3.3V/3.0V µP Reset
Notice: The information in this document is subject to change without notice
February 2005
rev 1.4
ASM1815
Absolute Maximum Ratings
Parameter
Voltage on V
CC
Voltage on RESET
Operating Temperature Range
Soldering Temperature (for 10 sec)
Storage Temperature
-55
Min
-0.5
-0.5
-40
Max
7
V
CC
+ 0.5
85
260
125
Unit
V
V
°C
°C
°C
ESD rating
HBM
MM
2
200
KV
V
NOTE: These are stress ratings only and functional use is not implied. Exposure to absolute maximum ratings for prolonged
periods of time may affect device reliability.
Electrical Characteristics
Unless otherwise noted, V
CC
= 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
Supply Voltage
Output Voltage
Output Current
Output Current
Operating Current
Operating Current
V
CC
Trip Point (ASM1815R-5)
V
CC
Trip Point (ASM1815R-10)
V
CC
Trip Point (ASM1815R-20)
Output Capacitance
V
CC
Detect to RESET Low
V
CC
Slew Rate
(V
CCTP
(MAX) to V
CCTP
(MIN)
V
CC
Slew Rate
(V
CCTP
(MIN) to V
CCTP
(MAX)
V
CC
Detect to RESET High
Symbol
V
CC
V
OH
I
OH
I
OL
I
CC
I
CC
V
CCTP
V
CCTP
V
CCTP
C
OUT
t
RPD
t
F
t
R
t
RPU
t
r
= 5µs
300
0
100
150
250
2
I
OUT
< 500 µA
Output = 2.4V, V
CC
> 2.7V
Output = 0.4V, V
CC
> 2.7V
V
CC
< 5.5V, RESET output open
V
CC
< 3.6V, RESET output open
2.98
2.80
2.47
+10
8
6
3.06
2.88
2.55
20
15
3.15
2.97
2.64
10
5
Conditions
Min
1.2
V
CC
- 0.5V
V
CC
- 0.1V
350
Typ
Max
5.5
Unit
V
V
µA
mA
µA
µA
V
V
V
pF
µs
µs
ns
ms
Note: The t
F
value is for reference in defining values for t
RPD
and should not be considered for proper operation or use.
Low Power, 3.3V/3.0V µP Reset
Notice: The information in this document is subject to change without notice
4 of 9
February 2005
rev 1.4
ASM1815
Package Dimension
Plastic SOT-23 (3-Pin)
D
B
E
H
S
e
A
C
L
a
A1
e1
Inches
Millimeters
Min
Max
Min
Max
Plastic SOT-23 (3-Pin)
A
A1
B
C
D
E
e
e1
H
L
a
S
0.030
0.002
0.012
0.003
0.110
0.047
0.046
0.006
0.020
0.008
0.120
0.055
0.75
0.05
0.30
0.08
2.80
1.20
0.95 BSC
1.9 BSC
2.10
0.40
0
o
1.17
0.15
0.50
0.20
3.04
1.40
0.037 BSC
0.075 BSC
0.083
0.016
0
o
0.104
0.024
8
o
2.64
0.60
8
o
NA
NA
5 of 9
Low Power, 3.3V/3.0V µP Reset
Notice: The information in this document is subject to change without notice
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