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參數(shù)資料
| 型號： | G692 |
| 廠商： | Electronic Theatre Controls, Inc. |
| 英文描述： | 4-Pin UP Voltage Monitors with Manual Reset Input |
| 中文描述： | 4引腳的電壓，帶有手動復位輸入監(jiān)視器 |
| 文件頁數(shù)： | 6/7頁 |
| 文件大?。?/td> | 171K |
| 代理商： | G692 |
Ver: 1.0
Sep 23, 2002
TEL: 886-3-5788833
http://www.gmt.com.tw
6
G692/G693
Global Mixed-mode Technology Inc.
Applications Information
Negative-Going V
CC
Transients
In addition to issuing a reset to the μP during power-up,
power-down,
and
brownout
G693L/G692H/G692L are relatively immune to short-
duration negative-going V
CC
transients (glitches).
conditions,
the
Figure1 shows typical transient duration vs. reset
comparator overdrive, for which the G693L/G692H/
G692L do not generate a reset pulse. The graph was
generated using a negative-going pulse applied to V
CC
,
starting 0.5V above the actual reset threshold and
ending below it by the magnitude indicated (reset
comparator overdrive). The graph indicates the maxi-
mum pulse width a negative-going V
CC
transient can
have without causing a reset pulse. As the magnitude
of the transient increases (goes farther below the reset
threshold), the maximum allowable pulse width de-
creases. Typically, for the G69_ _463 and G69_ _438,
a V
CC
transient that goes 100mV below the reset
threshold and lasts 15μs or less will not cause a reset
pulse. A 0.1μF bypass capacitor mounted as close as
possible to the V
CC
pin provides additional transient
immunity.
Ensuring a Valid Reset Output Down to V
CC
= 0
When V
CC
falls below 1V, the G692 RESET
output no
longer sinks current—it becomes an open circuit.
Therefore, high-impedance CMOS logic inputs con-
nected to RESET
can drift to undetermined voltages.
This presents no problem in most applications since
most μP and other circuitry is inoperative with
VCC
be-
low 1V. However, in applications where RESET
must
be valid down to 0V, adding a pull-down resistor to
RESET
causes any stray leakage currents to flow to
ground, holding RESET
low (Figure 2). R1’s value is
not critical; 100k
is large enough not to load RESET
and small enough to pull RESET
to ground.
A 100k
pull-up resistor to
VCC
is also recommended
for the G693L if RESET is required to remain valid for
V
CC
< 1V.
Figure 3. Interfacing to μPs with Bidirectional Reset
I/O
Figure 4. G693L Open-Drain
RESET
Output Allows
Use with Multiple Supplies
Interfacing to μPs with Bidirectional Reset Pins
Since the RESET
output on the G693L is open drain,
this device interfaces easily with μPs that have bidirec-
tional reset pins, such as the Motorola 68HC11. Con-
necting the μP supervisor’s RESET
output directly to
the microcontroller’s (μC’s) RESET
pin with a single
pull-up resistor allows either device to assert reset
(Figure 3).
G693L Open-Drain
RESET
Output Allows Use with
Multiple Supplies
Generally, the pull-up connected to the G693L will
connect to the supply voltage that is being monitored at
the IC’s V
CC
pin. However, some systems may use the
open-drain output to level-shift from the monitored sup-
ply to reset circuitry powered by some other supply
(Figure 4). Note that as the G693L’s V
CC
decreases
below 1V, so does the IC’s ability to sink current at
RESET . Also, with any pull-up, RESET
will be pulled
high as V
CC
decays toward 0. The voltage where this
occurs depends on the pull-up resistor value and the
voltage to which it is connected.
Benefits of Highly Accurate Reset Threshold
Most μP supervisor ICs have reset threshold voltages
between 5% and 10% below the value of nominal sup-
ply voltages. This ensures a reset will not occur within
5% of the nominal supply, but will occur when the sup-
ply is 10% below nominal.
When using ICs rated at only the nominal supply ±5%,
this leaves a zone of uncertainty where the supply is
between 5% and 10% low, and where the reset may or
may not be asserted.
The G69_ _463/G69_ _308 use highly accurate circuitry
to ensure that reset is asserted close to the 5% limit,
and long before the supply has declined to 10% below
nominal.
INPUT
GND
5V SYSTEM
V
CC
RESET
GND
G693
V
CC
R
PULL-UP
+3.3V
+5.0V
RESET
INPUT
GND
μP
V
CC
RESET
GND
G693
V
CC
V
CC
68HCXX
R
PULL-UP
RESET
MOTOROLA
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| G692H | 4-Pin UP Voltage Monitors with Manual Reset Input |
| G693 | 4-Pin UP Voltage Monitors with Manual Reset Input |
| G693L | 4-Pin UP Voltage Monitors with Manual Reset Input |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| G692H | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:4-Pin UP Voltage Monitors with Manual Reset Input |
| G693 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:4-Pin UP Voltage Monitors with Manual Reset Input |
| G693L | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:4-Pin UP Voltage Monitors with Manual Reset Input |
| G696 | 制造商:GMT 制造商全稱:Global Mixed-mode Technology Inc 功能描述:Microprocessor Reset IC |
| G696_06 | 制造商:GMT 制造商全稱:Global Mixed-mode Technology Inc 功能描述:Microprocessor Reset IC |
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