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參數(shù)資料
| 型號(hào)： | ASM812 |
| 廠商： | Alliance Semiconductor Corporation |
| 英文描述： | 4 Pin P Voltage Supervisor with Manual Reset |
| 中文描述： | 4引腳P的電壓監(jiān)控，帶有手動(dòng)復(fù)位 |
| 文件頁(yè)數(shù)： | 3/10頁(yè) |
| 文件大?。?/td> | 229K |
| 代理商： | ASM812 |
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Notice: The information in this document is subject to change without notice
ASM811, ASM812
4 Pin μP Voltage Supervisor with Manual Reset
October 2003
rev 1.0
Reset Output Operation
In μP / μC systems it is important to have the processor and
the system begin operation from a known state. A reset
output to a processor is provided to prevent improper
operation during power supply sequencing or low voltage
brown-out conditions.
The ASM811/812 are designed to monitor the system power
supply voltages and issue a reset signal when the levels are
out of range. RESET outputs are guaranteed to be active for
V
CC
above 1.1V. When V
CC
exceeds the reset threshold, an
internal timer keeps RESET active for the reset timeout
period, after which RESET becomes inactive (HIGH for the
ASM811 and LOW for the ASM812). If V
CC
drops below the
reset threshold, RESET automatically becomes active.
Alternatively, external circuitry or an operator can initiate this
condition using the Manual Reset (MR) pin. MR can be left
open if it is not used. MR can be driven by TTL/CMOS logic
or even an external switch.
Valid Reset with V
CC
under 1.1V
To ensure logic inputs connected to the ASM811 RESET pin
are in a known state when V
CC
is under 1.1V, a 100k
pull-
down resistor at RESET is needed. The value is not critical.
A 100k
pull-up resistor to V
CC
is needed with the ASM812.
Application Information
Negative VCC Transients
Typically short duration transients of 100mV amplitude and
20μs duration do not cause a false RESET. A 0.1μF capacitor
at V
CC
increses transient immunity.
Bidirectional Reset Pin Interfacing
The ASM811/812 can interface with μP / μC bi-directional
reset pins by connecting a 4.7k
resistor in series with the
ASM811/812 reset output and the μP/μC bi-directional reset
input pin.
Power supply
BUF
Buffered
RESET
V
CC
ASM811
GND
GND
RESET
RESET
Input
μC or μP
4.7k
Bi-directional I/O Pin
Figure 4: Bi-directional Reset Pin Interface
MR
V
CC
Power Supply
ASM811
RESET
GND
100k
V
CC
Power Supply
ASM812
RESET
GND
MR
MR
100k
0V
5V
V
CC
V
TH
T
RST
T
MRST
5V
0V
5V
0V
5V
0V
MR
RESET
RESET
ASM811
ASM812
Figure 1: Reset Timing and Manual Reset (MR)
Figures 2 & 3: RESET valid with V
CC
under 1.1V
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相關(guān)代理商/技術(shù)參數(shù) |
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| ASM812JEUS | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:4-Pin muP Voltage Supervisor with Manual Reset |
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| ASM812LEUS | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:4-Pin muP Voltage Supervisor with Manual Reset |
| ASM812LEUSF | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:4-Pin muP Voltage Supervisor with Manual Reset |
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