ASM1810
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
Low Power, 5V P Reset
- Active LOW, Push-Pull Output
General Description
The ASM1810 is a voltage supervisor with low-power, 5V P
active LOW Reset, Push-Pull output. Maximum supply current
over temperature is a low 20A.
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 low cost TO-92 and compact surface
mount SOT-23 packages.
Other low power products in this family include the ASM1811/
12/15/16/17, ASM1233D and ASM1233M.
Typical Operating Circuit
Key Features
Low Supply Current
20 A 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 and compact surface mount SOT-23 pack-
age
Push-Pull output for minimum current drain
Operating temperature -40C to +85C
Applications
Set-top boxes
Cellular phones
PDAs
Energy management systems
Embedded control systems
Printers
Single board computers
Block Diagram
Microprocessor
V
CC
RESET
RESET
GND
ASM1810
ASM1810
V
CC
RESET
Supply
Reference
Delay
150ms
Typical
Tolerance
Bias
+
-
2
ASM1810
V
CC
Supply
Delay
150ms
Typical
Tolerance
Bias
-
GND
RESET
Reference
+
1
3
3 of 9
Notice: The information in this document is subject to change without notice
Low Power, 5V P Reset
ASM1810
February 2005
rev 1.4
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.
Output Conditions
The ASM1810 active LOW reset signal is valid as long as V
CC
remains above 1.2V. However 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 100k
should be
adequate to maintain a valid connection.
Microprocessor
RESET
RESET
ASM1810
100k
Figure 1: RESET Valid to 0V V
CC
~
~
V
OH
RESET
~
t
RPU
V
CCTP
(MIN)
V
CCTP
V
CCTP
(MAX)
t
R
V
CC
~
Figure 2: Timing Diagram: Power-Up
~ ~
V
CCTP
(MIN)
V
CCTP
V
CCTP
(MAX)
t
F
V
CC
t
RPD
V
OL
RESET
Figure 3: Timing Diagram: Power-Down
ASM1810
4 of 9
Notice: The information in this document is subject to change without notice
Low Power, 5V P Reset
February 2005
rev 1.4
Absolute Maximum Ratings
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
Min
Max
Unit
Voltage on V
CC
-0.5
7
V
Voltage on RESET
-0.5
V
CC
+ 0.5
V
Operating Temperature Range
-40
85
C
Soldering Temperature (for 10 sec)
260
C
Storage Temperature
-55
125
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.
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
Supply voltage
V
CC
1.2
5.5
V
Output voltage
V
OH
I
OUT
< 500 A
V
CC
- 0.5V
V
CC
- 0.1V
V
Output Current
I
OH
Output = 2.4V, V
CC
> 2.7V
350
A
Output Current
I
OL
Output = 0.4V, V
CC
> 2.7V
+10
mA
Operating Current
I
CC
V
CC
< 5.5V, RESET output open
8
20
A
V
CC
Trip Point (ASM1810R-5)
V
CCTP
4.50
4.62
4.75
V
V
CC
Trip Point (ASM1810R-10)
V
CCTP
4.25
4.37
4.49
V
V
CC
Trip Point (ASM1810R-15)
V
CCTP
4.00
4.12
4.24
V
Output Capacitance
C
OUT
10
pF
V
CC
Detect to RESET Low
t
RPD
2
5
s
V
CC
Slew Rate
(V
CCTP
(MAX) to V
CCTP
(MIN)
t
F
300
s
V
CC
Slew Rate
(V
CCTP
(MIN) to V
CCTP
(MAX)
t
R
0
ns
V
CC
Detect to RESET High
t
RPU
t
r
= 5s
100
150
300
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.
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