October 2003
rev 1.0
ASM1810
Low Power, 5V µP Reset
- Active LOW, Push-Pull Output
Key Features
•
•
•
Low Supply Current
•20 µA maximum (5.5 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
Low-cost TO-92 package
Compact surface mount SOT-23 package
Push-Pull output for minimum current drain
Operating temperature -40°C to +85°C
General Description
The ASM1810 is a voltage supervisor with low-power, 5V µP
active LOW Reset, Push-Pull output. Maximum supply current
over temperature is a low 20µA.
The ASM1810 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 15%. 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 ASM1810 is designed with a push-pull output stage and
operates over the extended industrial temperature range.
Devices are available in compact surface mount SOT-23
packages and 3-lead TO-92 packages.
Other low power products in this family include the ASM1811/
12/15/16/17, ASM1233D and ASM1233M.
Applications
•
•
•
•
•
•
•
Set-top boxes
Cellular phones
PDAs
Energy management systems
Embedded control systems
Printers
Single board computers
Typical Operating Circuit
Block Diagram
V
CC
2
V
CC
ASM1810
Microprocessor
RESET
RESET
Supply
Tolerance
Bias
ASM1810
+
-
Reference
Delay
150ms
Typical
1
RESET
GND
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
October 2003
rev 1.0
ASM1810
Pin Configuration
SOT-23
RESET
1
ASM1810-X
3
TO-92*
ASM1810-X
GND
V
CC
2
1
2
3
*
See Ordering Information
Pin Description
Pin #
1
2
3
Pin Name
RESET
V
CC
GND
Description
Active LOW reset output
Power supply input
Ground
Low Power, 5V µP Reset
Notice: The information in this document is subject to change without notice
2 of 8
October 2003
rev 1.0
ASM1810
Application Information
Operation - Power Monitor
The
ASM1810
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 monitored
power supply voltage is below the reset threshold. When an
out-of-tolerance V
CC
voltage is detected, the RESET signal is
asserted. On power-up, RESET is kept active (LOW) for
approximately 150ms after the power supply voltage has
reached the selected tolerance. This allows the power supply
and microprocessor to stabilize before RESET is released.
V
CC
V
CCTP
(MIN)
t
R
V
CCTP
(MAX)
V
CCTP
~
~
t
RPU
V
OH
ASM1810
Microprocessor
RESET
100kΩ
RESET
~
~
RESET
Figure 2: Timing Diagram: Power-Up
Figure 1: RESET Valid to 0V V
CC
V
CC
V
CCTP
(MAX)
V
CCTP
V
CCTP
(MIN)
t
F
Output Conditions
The ASM1810 active LOW reset signal is valid as long as V
CC
remains below 1.2V. The RESET output on the ASM1810 uses
a push-pull drive stage that can maintain a 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
1). 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.
RESET
t
RPD
V
OL
Figure 3: Timing Diagram: Power-Down
~
~
3 of 8
Low Power, 5V µP Reset
Notice: The information in this document is subject to change without notice
October 2003
rev 1.0
ASM1810
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
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 VCC = 1.25V to 5.5V and specifications are over the operating temperature range of -40
0
c to +85
0
c. All
voltages are referenced to ground.
Parameter
Supply voltage
Output voltage
Output Current
Output Current
Operating Current
V
CC
Trip Point (ASM1810-5)
V
CC
Trip Point (ASM1810-10)
V
CC
Trip Point (ASM1810-15)
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
V
CCTP
V
CCTP
V
CCTP
C
OUT
t
RPD
t
F
t
R
t
RPU
t
r
= 5µs
300
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
4.50
4.25
4.00
+10
8
4.62
4.37
4.12
20
4.75
4.49
4.24
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
V
V
V
pF
µs
µs
0
100
150
300
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, 5V µP Reset
Notice: The information in this document is subject to change without notice
4 of 8
October 2003
rev 1.0
ASM1810
Family Selection Guide
Part #
ASM1810
ASM1811
ASM1812
ASM1815
ASM1816
ASM1817
ASM1233D
ASM1233M
RESET Voltage (V)
4.620, 4.370, 4.120
4.620, 4.350, 4.130
4.620, 4.350, 4.130
3.060, 2.880, 2.550
3.060, 2.880, 2.550
3.060, 2.880, 2.550
4.625, 4.375, 4.125
4.625, 4.375, 2.720
RESET Time
(ms)
150
150
150
150
150
150
350
350
Output Stage
Push-Pull
Open-Drain
Push-Pull
Push-Pull
Open-Drain
Push-Pull
Open-Drain
Open-Drain
RESET Polarity
LOW
LOW
HIGH
LOW
LOW
HIGH
LOW
LOW
Low Power, 5V µP Reset
Notice: The information in this document is subject to change without notice
5 of 8
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