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參數(shù)資料
| 型號(hào)： | MAX6454 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | uP Supervisors with Separate VCC Reset and Manual Reset Outputs |
| 中文描述： | 微處理器監(jiān)控電路，帶有獨(dú)立的VCC復(fù)位輸出和手動(dòng)復(fù)位輸出 |
| 文件頁(yè)數(shù)： | 7/10頁(yè) |
| 文件大?。?/td> | 189K |
| 代理商： | MAX6454 |
M
μP Supervisors with Separate V
CC
Reset and
Manual Reset Outputs
_______________________________________________________________________________________
7
Applications Information
Interrupt Before Reset
To minimize data loss and speed system recovery/test,
many applications interrupt the processor or reset only
portions of the system before a processor hard reset is
asserted. The extended setup time of the MAX6455/
MAX6456
MR
input allows the same pushbutton (Figure
4) to control both the interrupt and hard reset functions.
If the pushbutton is closed for less than 3.36s (typ), the
processor is only interrupted (
MROUT
). If the system
still does not respond properly, the pushbutton can be
closed for the full extended setup period (3.36s typ) to
hard reset the processor (
RESET
). If desired, connect a
LED to the
RESET
output to turn off (or on) to signify
when the pushbutton is closed long enough for a hard
reset (the same LED can be used as the front panel
power-on display).
Interfacing to Other Voltages
for Logic Compatibility
The open-drain
RESET
output can be used to interface
to a μP with other logic levels. As shown in Figure 5, the
open-drain output can be connected to voltages from 0
to 6V.
Generally, the pullup resistor connected to the
RESET
connects to the supply voltage being monitored at the
IC
’
s V
CC
pin. However, some systems might use the
open-drain output to level-shift from the monitored sup-
ply to reset circuitry powered by some other supply
(Figure 5). Keep in mind that as the supervisor
’
s V
CC
decreases toward 1V, so does the IC
’
s ability to sink
current at
RESET
(
RESET
is pulled high as V
CC
decays
toward 0). The voltage where this occurs depends on
the pullup resistor value and the voltage to which it is
connected.
Ensuring a Valid
RESET
Down to V
CC
= 0V
(Push-Pull
RESET
)
When V
CC
falls below 1V,
RESET
current-sinking capa-
bilities decline drastically. The high-impedance CMOS-
logic inputs connected to
RESET
can drift to
undetermined voltages. This presents no problem in
most applications, because most μPs and other circuit-
ry do not operate with V
CC
below 1V.
In applications where
RESET
must be valid down to 0V,
add a pulldown resistor between
RESET
and GND for
the push/pull outputs. The resistor sinks any stray leak-
age currents, holding
RESET
low (Figure 6). The value
of the pulldown resistor is not critical; 100k
is large
enough not to load
RESET
and small enough to pull
RESET
to ground. The external pulldown cannot be
used with the open-drain reset outputs.
Transient Immunity
In addition to issuing a reset to the μP during power-up,
power-down and brownout conditions, these supervisors
are relatively immune to short duration falling transients
(glitches). The graph Maximum Transient Duration vs.
Reset Threshold Overdrive in the
Typical Operating
Characteristics
section shows this relationship.
The area below the curves of the graph is the region in
which these devices typically do not generate a reset
pulse. This graph was generated using a negative
going pulse applied to V
CC
, starting above the actual
reset threshold (V
TH
) and ending below it by the magni-
tude indicated (reset-threshold overdrive). As the mag-
nitude of the transient increases (V
CC
goes further
below the reset threshold), the maximum allowable
pulse width decreases. Typically, a V
CC
transient that
goes 100mV below the reset threshold and lasts 20μs
or less does not cause a reset pulse to be issued.
MAX6453
MAX6455
RSTIN
V
CC
R1
R2
RESET
GND
V
MON_TH
= 0.63 x (R1 + R2) / R2
V
MON_TH
V
CC
Figure 3. Calculating The Monitored Threshold Voltages
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX6454UT16S | 制造商:Maxim Integrated Products 功能描述:MICROPROCESSOR SUPERVISORS WITH SEP - Cut Tape Product |
| MAX6454UT16S+ | 制造商:Maxim Integrated Products 功能描述:PROCESSOR SUPERVISOR ADJV 7UA 6PIN SOT-23 - Rail/Tube 制造商:Rochester Electronics LLC 功能描述: |
| MAX6454UT16S+T | 功能描述:監(jiān)控電路 Dual uPower Reset Circuit RoHS:否 制造商:STMicroelectronics 監(jiān)測(cè)電壓數(shù): 監(jiān)測(cè)電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開關(guān):No Backup 上電復(fù)位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| MAX6454UT16S-T | 功能描述:監(jiān)控電路 RoHS:否 制造商:STMicroelectronics 監(jiān)測(cè)電壓數(shù): 監(jiān)測(cè)電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開關(guān):No Backup 上電復(fù)位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| MAX6454UT17S | 制造商:Maxim Integrated Products 功能描述:MICROPROCESSOR SUPERVISORS WITH SEP - Rail/Tube |
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