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參數(shù)資料
| 型號： | 74VHC123ASJX |
| 廠商： | Fairchild Semiconductor |
| 文件頁數(shù)： | 10/14頁 |
| 文件大?。?/td> | 0K |
| 描述： | MULTIVIBRATOR DUAL MONO 16SOP |
| 標準包裝： | 2,000 |
| 系列： | 74VHC |
| 邏輯類型： | 單穩(wěn)態(tài) |
| 獨立電路： | 2 |
| 施密特觸發(fā)器輸入： | 無 |
| 傳輸延遲： | 8.1ns |
| 輸出電流高，低： | 8mA，8mA |
| 電源電壓： | 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-SOIC（0.209"，5.30mm 寬） |
| 供應商設備封裝： | 16-SOP |
| 包裝： | 帶卷 (TR) |
74VHC123A
Dual
Retrig
g
erab
le
Monostab
le
Multivibrator
1993 Fairchild Semiconductor Corporation
www.fairchildsemi.com
74VHC123A Rev. 1.2
5
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 cur-
rent 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 sig-
nal; 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 volt-
age level at the Rx/Cx node drops. If the Rx/Cx volt-
age 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 operating.
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 fall-
ing to rising. When Rx/Cx reaches the internal refer-
ence voltage VrefH, the output of C2 becomes LOW,
the output 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
follows:
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
trigger, 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
output 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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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| 74VHC123ASJX_NL | 功能描述:單穩(wěn)態(tài)多諧振蕩器 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 |
| 74VHC125 | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Quad Buffer with 3-STATE Outputs |
| 74VHC125_04 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:QUAD BUS BUFFERS (3-STATE) |
| 74VHC125_07 | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Quad Buffer with 3-STATE Outputs |
| 74VHC125BQ | 制造商:NXP Semiconductors 功能描述:Cut Tape 制造商:NXP Semiconductors 功能描述:Bulk 制造商:NXP Semiconductors 功能描述:IC QUAD BUFF/DVR TRI-ST DH 制造商:NXP Semiconductors 功能描述:Buffer/Line Driver 4-CH Non-Inverting 3-ST CMOS 14-Pin DHVQFN EP T/R |
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