参数资料
| 型号： | NE555DX |
| 厂商： | Fairchild Semiconductor |
| 文件页数： | 2/13页 |
| 文件大小： | 0K |
| 描述： | IC OSC MONO TIMING 8-SOP |
| 标准包装： | 3,000 |
| 类型： | 555 型，计时器/振荡器（单路） |
| 电源电压： | 4.5 V ~ 16 V |
| 电流 - 电源： | 7.5mA |
| 工作温度： | 0°C ~ 70°C |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 8-SOP |
| 安装类型： | 表面贴装 |
LM555
—
Single
T
imer
2002 Fairchild Semiconductor Corporation
www.fairchildsemi.com
LM555 Rev. 1.1.0
10
In Figure 14, current source is created by PNP transistor Q1 and resistor R1, R2, and RE.
For example, if VCC = 15 V, RE = 20 kΩ, R1 = 5 kΩ, R2 = 10 kΩ, and VBE = 0.7 V,
VE=0.7 V+10 V=10.7 V, and
IC=(15-10.7) / 20 k=0.215 mA.
When the trigger starts in a timer configured as shown in Figure 14, the current flowing through capacitor C1 becomes
a constant current generated by PNP transistor and resistors.
Hence, the VC is a linear ramp function as shown in Figure 15. The gradient S of the linear ramp function is defined as
follows:
Here the Vp-p is the peak-to-peak voltage.
If the electric charge amount accumulated in the capacitor is divided by the capacitance, the VC comes out as follows:
V = Q/C
(15)
The above equation divided on both sides by t gives:
and may be simplified into the following equation:
S = I/C
(17)
In other words, the gradient of the linear ramp function appearing across the capacitor can be obtained by using the
constant current flowing through the capacitor.
If the constant current flow through the capacitor is 0.215 mA and the capacitance is 0.02
μF, the gradient of the ramp
function at both ends of the capacitor is S = 0.215 m / 0.022
μ = 9.77 V/ms.
I
C
V
CC
V
E
–
R
E
---------------------------
=12
()
Here, V
E is
V
E
V
BE
R
2
R
1
R
2
+
----------------------V
CC
+
=13
()
S
V
pp
–
----------------
=14
()
V
----
Q §
C
-------------
=16
()
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相关代理商/技术参数 |
参数描述 |
|---|---|
| NE555F | 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:Timer |
| NE555FK | 制造商:TI 制造商全称:Texas Instruments 功能描述:PRECISION TIMERS |
| NE555G-D08-T | 制造商:UTC-IC 制造商全称:UTC-IC 功能描述:SINGLE TIMER |
| NE555G-S08-R | 制造商:UTC-IC 制造商全称:UTC-IC 功能描述:SINGLE TIMER |
| NE555G-S08-T | 制造商:UTC-IC 制造商全称:UTC-IC 功能描述:SINGLE TIMER |
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