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參數(shù)資料
| 型號： | 74VHC123A |
| 廠商： | Fairchild Semiconductor Corporation |
| 英文描述： | Automotive Catalog Dual D-Type Positive-Edge-Triggered Flip-Flops With Clear and Preset 14-SOIC -40 to 125 |
| 中文描述： | 雙Retriggerable單穩(wěn)態(tài)觸發(fā)器 |
| 文件頁數(shù)： | 3/9頁 |
| 文件大小： | 107K |
| 代理商： | 74VHC123A |
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Timing Chart
Functional Description
1. Stand-by State
The external capacitor (Cx) is fully charged to VCC in
the Stand-by State. That means, before triggering, the
QP and QN transistors which are connected to the Rx/
Cx node are in the off state. Two comparators that
relate to the timing of the output pulse, and two refer-
ence voltage supplies turn off. The total supply current
is only leakage current.
2. Trigger Operation
Trigger operation is effective in any of the following
three cases. First, the condition where the A input is
LOW, and B input has a rising signal; second, where
the B input is HIGH, and the A input has a falling signal;
and third, where the A input is LOW and the B input is
HIGH, and the CLR input has a rising signal.
After a trigger becomes effective, comparators C1 and
C2 start operating, and QN is turned on. The external
capacitor discharges through QN. The voltage level at
the Rx/Cx node drops. If the Rx/Cx voltage level falls to
the internal reference voltage VrefL, the output of C1
becomes LOW. The flip-flop is then reset and QN turns
off. At that moment C1 stops but C2 continues operat-
ing.
After QN turns off, the voltage at the Rx/Cx node starts
rising at a rate determined by the time constant of
external capacitor Cx and resistor Rx.
Upon triggering, output Q becomes HIGH, following
some delay time of the internal F/F and gates. It stays
HIGH even if the voltage of Rx/Cx changes from falling
to rising. When Rx/Cx reaches the internal reference
voltage VrefH, the output of C2 becomes LOW, the out-
put Q goes LOW and C2 stops its operation. That
means, after triggering, when the voltage level of the
Rx/Cx node reaches VrefH, the IC returns to its
MONOSTABLE state.
With large values of Cx and Rx, and ignoring the dis-
charge time of the capacitor and internal delays of the
IC, the width of the output pulse, tW (OUT), is as fol-
lows:
tW (OUT) = 1.0 Cx Rx
3. Retrigger operation (74VHC123A)
When a new trigger is applied to either input A or B
while in the MONOSTABLE state, it is effective only if
the IC is charging Cx. The voltage level of the Rx/Cx
node then falls to VrefL level again. Therefore the Q
output stays HIGH if the next trigger comes in before
the time period set by Cx and Rx.
If the new trigger is very close to a previous trigger,
such as an occurrence during the discharge cycle, it
will have no effect.
The minimum time for a trigger to be effective 2nd trig-
ger, tRR (Min), depends on VCC and Cx.
4. Reset Operation
In normal operation, the CLR input is held HIGH. If
CLR is LOW, a trigger has no affect because the Q out-
put is held LOW and the trigger control F/F is reset.
Also, Qp turns on and Cx is charged rapidly to VCC.
This means if CLR is set LOW, the IC goes into a wait
state.
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相關(guān)代理商/技術(shù)參數(shù) |
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| 74VHC123A_07 | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Dual Retriggerable Monostable Multivibrator |
| 74VHC123AFT | 功能描述:Monostable Multivibrator 9.6ns 16-TSSOP 制造商:toshiba semiconductor and storage 系列:汽車級，AEC-Q100，74VHC 包裝:剪切帶（CT） 零件狀態(tài):停產(chǎn) 邏輯類型:單穩(wěn)態(tài) 獨立電路:2 施密特觸發(fā)器輸入:無 傳播延遲:9.6ns 電流 - 輸出高，低:8mA，8mA 電壓 - 電源:2 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:16-TSSOP（0.173"，4.40mm 寬） 供應(yīng)商器件封裝:16-TSSOP 標準包裝:1 |
| 74VHC123AM | 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 |
| 74VHC123AM | 制造商:Fairchild Semiconductor Corporation 功能描述:74VHC CMOS SMD 74VHC123 SOIC16 |
| 74VHC123AM_Q | 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 |
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