An astable timer operation " />
參數(shù)資料
型號(hào): LM555CMX
廠商: Fairchild Semiconductor
文件頁(yè)數(shù): 10/13頁(yè)
文件大?。?/td> 0K
描述: IC OSC MONO TIMING 8-SOP
標(biāo)準(zhǔn)包裝: 1
類型: 555 型,計(jì)時(shí)器/振蕩器(單路)
電源電壓: 4.5 V ~ 16 V
電流 - 電源: 7.5mA
工作溫度: 0°C ~ 70°C
封裝/外殼: 8-SOIC(0.154",3.90mm 寬)
包裝: 標(biāo)準(zhǔn)包裝
供應(yīng)商設(shè)備封裝: 8-SOIC
安裝類型: 表面貼裝
其它名稱: LM555CMXFSDKR
LM555
Single
T
imer
2002 Fairchild Semiconductor Corporation
www.fairchildsemi.com
LM555 Rev. 1.1.0
6
An astable timer operation is achieved by adding resistor RB to Figure 2 and configuring as shown on Figure 6. In the
astable operation, the trigger terminal and the threshold terminal are connected so that a self-trigger is formed, operat-
ing as a multi-vibrator. When the timer output is high, its internal discharging transistor. turns off and the VC1 increases
by exponential function with the time constant (RA+RB)*C.
When the VC1, or the threshold voltage, reaches 2 VCC/3; the comparator output on the trigger terminal becomes
high, resetting the F/F and causing the timer output to become low. This turns on the discharging transistor and the C1
discharges through the discharging channel formed by RB and the discharging transistor. When the VC1 falls below
VCC/3, the comparator output on the trigger terminal becomes high and the timer output becomes high again. The dis-
charging transistor turns off and the VC1 rises again.
In the above process, the section where the timer output is high is the time it takes for the VC1 to rise from VCC/3 to 2
VCC/3, and the section where the timer output is low is the time it takes for the VC1 to drop from 2 VCC/3 to VCC/3.
When timer output is high, the equivalent circuit for charging capacitor C1 is as follows:
Since the duration of the timer output high state (tL) is the amount of time it takes for the VC1(t) to reach 2 VCC/3,
Figure 8. Waveforms of Astable Operation
Vcc
R
A
R
B
C1
Vc1(0-)=Vcc/3
C
1
dv
c1
dt
-------------
V
cc
V0-
()
R
A
R
B
+
-------------------------------
=1
()
V
C1
0+
()
V
CC
3
=2
()
V
C1
t
()
V
CC
1
2
3
---e
-
t
R
A
R
B
+
()C1
-------------------------------------
=3
()
V
C1
t
()
2
3
---V
CC
V
=
CC
1
2
3
---e
-
t
H
R
A
R
B
+
()C1
-------------------------------------
=4
()
t
H
C
1
R
A
R
B
+
()In2 0.693 R
A
R
B
+
()C
1
=
=5
()
相關(guān)PDF資料
PDF描述
VE-B33-IU-S CONVERTER MOD DC/DC 24V 200W
74VHC157MTCX MULTIPLEXER QUAD 2IN 16TSSOP
VI-B1N-IU-S CONVERTER MOD DC/DC 18.5V 200W
VI-B1H-IU-S CONVERTER MOD DC/DC 52V 200W
VI-B1F-IU-S CONVERTER MOD DC/DC 72V 200W
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LM555CMX NOPB 制造商:Texas Instruments 功能描述:Standard Timer Single 8-Pin SOIC T/R
LM555CMX 制造商:Fairchild Semiconductor Corporation 功能描述:TIMER IC ROHS COMPLIANT:NO
LM555CMX/260C 制造商:Texas Instruments 功能描述:
LM555CMX/NOPB 功能描述:計(jì)時(shí)器和支持產(chǎn)品 TIMER RoHS:否 制造商:Micrel 類型:Standard 封裝 / 箱體:SOT-23 內(nèi)部定時(shí)器數(shù)量:1 電源電壓-最大:18 V 電源電壓-最小:2.7 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
LM555CMX/NOPB 制造商:Texas Instruments 功能描述:IC TIMER SINGLE 16V 8-SOIC 制造商:Texas Instruments 功能描述:IC, TIMER, SINGLE, 16V, 8-SOIC