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參數資料
| 型號： | LMC555CBP |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 運動控制電子 |
| 英文描述： | CMOS Timer |
| 中文描述： | PULSE; RECTANGULAR, 3 MHz, TIMER, PBGA8 |
| 封裝： | ROHS COMPLIANT, MO-211BC, SMD-8 |
| 文件頁數： | 6/12頁 |
| 文件大小： | 318K |
| 代理商： | LMC555CBP |
Application Info
(Continued)
The charge time (output high) is given by
t
1
= Ln2 (R
A
+ R
B
)C
And the discharge time (output low) by:
t
2
= Ln2 (R
B
)C
Thus the total period is:
T = t
1
+ t
2
= Ln2 (R
A
+ R
B
)C
The frequency of oscillation is:
Figure 6 may be used for quick determination of these RC
Values. The duty cycle, as a fraction of total period that the
output is low, is:
FREQUENCY DIVIDER
The monostable circuit of Figure 1 can be used as a fre-
quency divider by adjusting the length of the timing cycle.
Figure 7shows the waveforms generated in a divide by three
circuit.
PULSE WIDTH MODULATOR
When the timer is connected in the monostable mode and
triggered with a continuous pulse train, the output pulse
width can be modulated by a signal applied to the Control
Voltage Terminal. Figure 8 shows the circuit, and in Figure 9
are some waveform examples.
PULSE POSITION MODULATOR
This application uses the timer connected for astable opera-
tion, as in Figure 10 with a modulating signal again applied
to the control voltage terminal. The pulse position varies with
DS008669-12
V
= 5V
TIME = 20 μs/Div.
R
A
= 3.9k
R
= 9k
C = 0.01μF
Top Trace: Output 5V/Div.
Bottom Trace: Capacitor Voltage 1V/Div.
FIGURE 5. Astable Waveforms
DS008669-13
FIGURE 6. Free Running Frequency
DS008669-14
V
CC
= 5V
TIME = 20 μs/Div.
R
= 9.1 k
C = 0.01μF
Top Trace: Input 4V/Div.
Middle Trace: Output 2V/Div.
Bottom Trace: Capacitor 2V/Div.
FIGURE 7. Frequency Divider Waveforms
DS008669-20
FIGURE 8. Pulse Width Modulator
DS008669-15
V
CC
= 5V
TIME = 0.2 ms/Div.
R
A
= 9.1 k
C = 0.01μF
FIGURE 9. Pulse Width Modulator Waveforms
Top Trace: Modulation 1V/Div.
Bottom Trace: Output Voltage 2V/Div.
L
www.national.com
6
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相關代理商/技術參數 |
參數描述 |
|---|---|
| LMC555CBP/NOPB | 制造商:Texas Instruments 功能描述:Standard Timer Single 8-Pin uSMD T/R |
| LMC555CBPEVAL | 功能描述:EVALUATION BOARD FOR LMC555CBP RoHS:是 類別:編程器，開發系統 >> 評估演示板和套件 系列:- 標準包裝:1 系列:PCI Express® (PCIe) 主要目的:接口，收發器，PCI Express 嵌入式:- 已用 IC / 零件:DS80PCI800 主要屬性:- 次要屬性:- 已供物品:板 |
| LMC555CBPX | 制造商:Rochester Electronics LLC 功能描述: 制造商:Texas Instruments 功能描述: |
| LMC555CBPX/NOPB | 功能描述:IC OSC MONO TMING 3MHZ 8MICROSMD RoHS:是 類別:集成電路 (IC) >> 時鐘/計時 - 可編程計時器和振蕩器 系列:- 產品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:45 系列:- 類型:溫度 - 補償晶體振蕩器（TCXO） 計數:- 頻率:25MHz 電源電壓:3.135 V ~ 3.465 V 電流 - 電源:1.5mA 工作溫度:-40°C ~ 85°C 封裝/外殼:16-SOIC（0.295"，7.50mm 寬） 包裝:管件 供應商設備封裝:16-SOIC W 安裝類型:表面貼裝 |
| LMC555CH | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:CMOS Timer(86.50 k) |
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