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參數(shù)資料
| 型號： | M54HC221AF1R |
| 廠商： | 意法半導(dǎo)體 |
| 英文描述： | Low-Power Mono ADC / Stereo DAC with 6 audio inputs and HP/Speaker Amplifier 48-VQFN -40 to 85 |
| 中文描述： | 雙單穩(wěn)態(tài)觸發(fā)器 |
| 文件頁數(shù)： | 3/14頁 |
| 文件大?。?/td> | 288K |
| 代理商： | M54HC221AF1R |
BLOCK DIAGRAM
Note:
(1)Cx, Rx, Dxare external components.
(2)Dx isa clamping diode.
Theexternal capacitor ischarged toV
CC
inthestand-by state, i.e.no trigger.Whenthesupply voltageisturned off Cxisdischarged mainly
through an internal parasitic diode (see figures). IfCx is sufficiently large and V
CC
decreases rapidy, there will besomepossibility ofda-
maging theI.C.witha surge currentor latch-up. If the voltage supply filtercapacitor is large enough and V
CC
decrease slowly,thesurge
current is automatically limited and damage theI.C. isavoided. Themaximum forward current of the parasitic diode isapproximately 20
mA.In cases where Cx islarge the time takenforthe supply voltage to fallto 0.4 V
CC
canbecalculated as follows:
t
f
≥
(V
CC
– 0.7)
Cx/20mA
Incases where t
f
istooshort an external clamping diode is required toprotect theI.C. fromthesurge current.
FUNCTIONAL DESCRIPTION
STAND-BY STATE
The external capacitor, Cx, is fully charged to V
CC
inthe stand-bystate.Hence, before triggering, tran-
sistorQpandQn (connected tothe Rx/Cxnode) are
both turned-off. The two comparators that control
the timing and the two reference voltage sources
stop operating. The total supply current istherefore
only leakage current.
TRIGGEROPERATION
Triggering occurswhen :
1
st
) A is”low” and Bhas a fallingedge;
2
nd
) B is”high” and Ahas a rising edge ;
3
rd
) Aislowand Bis high and C1 has a risingedge.
After the multivibrator has been retriggered com-
paratorC1 and C2 start operating and Qn isturned
on. Cx then discharges through Qn. The voltage at
the node R/C external falls.
Whenitreaches V
REFL
theoutput of comparator C1
becomeslow. Thisinturnresets theflip-flop andQn
is turnedoff.
At this point C1 stops functioning but C2 continues
to operate.
ThevoltageatR/Cexternalbegins torise withatime
constant set by the external components Rx, Cx.
Triggering the multivibratorcausesQtogohigh after
internal delay due to the flip-flop and the gate. Qre-
mains high until the voltage at R/C external rises
againto V
REFH
. Atthis point C2output goeslowand
O goes low. C2 stop operating. That means that
after triggering when the voltage R/C external re-
turns to V
REFH
the multivibrator has returned to its
MONOSTABLE STATE. In the case where Rx
Cx
are large enoughand the discharge time of the ca-
pacitorand thedelay timein theI.C.can be ignored,
the width of the output pulse tw (out) is as follows :
t
W(OUT)
= 0.70 Cx
Rx (HC221)
t
W(OUT)
= Cx
Rx (HC221A)
RESETOPERATION
CL isnormallyhigh. If CLislow,thetriggeris not ef-
fective because Q output goes low and trigger con-
trol flip-flop is reset.
Also transistor Op is turned on and Cx is charged
quickyto V
CC
. This means if CL input goes low, the
IC becomes waiting state both inoperating and non
operating state.
M54/M74HC221/221A
3/14
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PDF描述 |
|---|---|
| M54HC221M1R | Low-Power Mono ADC / Stereo DAC with 6 audio inputs and HP/Speaker Amplifier 48-VQFN -40 to 85 |
| M54HC221C1R | DUAL MONOSTABLE MULTIVIBRATOR |
| M54HC221AM1R | DUAL MONOSTABLE MULTIVIBRATOR |
| M54HC221AB1R | DUAL MONOSTABLE MULTIVIBRATOR |
| M54HC237 | Low-Power Mono ADC / Stereo DAC with 6 audio inputs and HP/Speaker Amplifier 48-VQFN -40 to 85 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| M54HC221AM1R | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:DUAL MONOSTABLE MULTIVIBRATOR |
| M54HC221B1R | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:DUAL MONOSTABLE MULTIVIBRATOR |
| M54HC221C1R | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:DUAL MONOSTABLE MULTIVIBRATOR |
| M54HC221F1R | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:DUAL MONOSTABLE MULTIVIBRATOR |
| M54HC221M1R | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:DUAL MONOSTABLE MULTIVIBRATOR |
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