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參數(shù)資料
| 型號： | MM74HC423AMX_NL |
| 廠商： | FAIRCHILD SEMICONDUCTOR CORP |
| 元件分類： | 諧振器 |
| 英文描述： | HC/UH SERIES, DUAL MONOSTABLE MULTIVIBRATOR, PDSO16 |
| 封裝： | 0.150 INCH, LEAD FREE, MS-012, SOIC-16 |
| 文件頁數(shù)： | 4/10頁 |
| 文件大小： | 129K |
| 代理商： | MM74HC423AMX_NL |
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MM74HC423A
Theory of Operation
FIGURE 1.
TRIGGER OPERATION
As shown in Figure 1 and the Logic Diagram before an
input trigger occurs, the one-shot is in the quiescent state
with the Q output LOW, and the timing capacitor CEXT com-
pletely charged to VCC. When the trigger input A goes from
VCC to GND (while inputs B and clear are held to VCC) a
valid trigger is recognized, which turns on comparator C1
and N-Channel transistor N11. At the same time the output
latch is set. With transistor N1 on, the capacitor CEXT rap-
idly discharges toward GND until VREF1 is reached. At this
point the output of comparator C1 changes state and tran-
sistor N1 turns OFF. Comparator C1 then turns OFF while
at the same time comparator C2 turns on. With transistor
N1 OFF, the capacitor CEXT begins to charge through the
timing resistor, REXT, toward VCC. When the voltage across
CEXTequals VREF2, comparator C2 changes state causing
the output latch to reset (Q goes LOW) while at the same
time disabling comparator C2. This ends the timing cycle
with the one-shot in the quiescent state, waiting for the next
trigger.
A valid trigger is also recognized when trigger input B goes
from GND to VCC (while input A is at GND and input clear
is at VCC2.)
It should be noted that in the quiescent state CEXTis fully
charged to VCC causing the current through resistor REXT
to be zero. Both comparators are “OFF” with the total
device current due only to reverse junction leakages. An
added feature of the MM74HC423A is that the output latch
is set via the input trigger without regard to the capacitor
voltage. Thus, propagation delay from trigger to Q is inde-
pendent of the value of CEXT, REXT, or the duty cycle of the
input waveform.
RETRIGGER OPERATION
The MM74HC423A is retriggered if a valid trigger occurs 3
followed by another trigger 4 before the Q output has
returned to the quiescent (zero) state. Any retrigger, after
the timing node voltage at pin or has begun to rise from
VREF1, but has not yet reached VREF2, will cause an
increase in output pulse width T. When a valid retrigger is
initiated 4, the voltage at the R/CEXT pin will again drop to
VREF1 before progressing along the RC charging curve
toward VCC. The Q output will remain high until time T, after
the last valid retrigger.
Because the trigger-control circuit flip-flop resets shortly
after CX has discharged to the reference voltage of the
lower reference circuit, the minimum retrigger time, trr is a
function of internal propagation delays and the discharge
time of CX:
Another removal/retrigger time occurs when a short clear
pulse is used. Upon receipt of a clear, the one shot must
charge the capacitor up to the upper trip point before the
one shot is ready to receive the next trigger. This time is
dependent on the capacitor used and is approximately:
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| MM74HC423AN | 功能描述:單穩(wěn)態(tài)多諧振蕩器 Dual Multivibrator RoHS:否 制造商:Texas Instruments 每芯片元件:1 邏輯系列:LVC 邏輯類型:Monostable Multivibrator 封裝 / 箱體:SSOP-8 傳播延遲時間:18.6 ns 高電平輸出電流:- 32 mA 低電平輸出電流:32 mA 電源電壓-最大:5.5 V 電源電壓-最小:1.65 V 最大功率耗散: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Reel |
| MM74HC423ASJ | 功能描述:單穩(wěn)態(tài)多諧振蕩器 Dual Multivibrator RoHS:否 制造商:Texas Instruments 每芯片元件:1 邏輯系列:LVC 邏輯類型:Monostable Multivibrator 封裝 / 箱體:SSOP-8 傳播延遲時間:18.6 ns 高電平輸出電流:- 32 mA 低電平輸出電流:32 mA 電源電壓-最大:5.5 V 電源電壓-最小:1.65 V 最大功率耗散: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Reel |
| MM74HC423ASJX | 功能描述:單穩(wěn)態(tài)多諧振蕩器 Dual Multivibrator RoHS:否 制造商:Texas Instruments 每芯片元件:1 邏輯系列:LVC 邏輯類型:Monostable Multivibrator 封裝 / 箱體:SSOP-8 傳播延遲時間:18.6 ns 高電平輸出電流:- 32 mA 低電平輸出電流:32 mA 電源電壓-最大:5.5 V 電源電壓-最小:1.65 V 最大功率耗散: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Reel |
| MM74HC4316 | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Quad Analog Switch with Level Translator |
| MM74HC4316M | 功能描述:模擬開關(guān) IC Quad Analog Switch RoHS:否 制造商:Texas Instruments 開關(guān)數(shù)量:2 開關(guān)配置:SPDT 開啟電阻（最大值）:0.1 Ohms 切換電壓（最大）: 開啟時間（最大值）: 關(guān)閉時間（最大值）: 工作電源電壓:2.7 V to 4.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:DSBGA-16 |
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