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參數(shù)資料
| 型號： | LM3524D |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | Regulating Pulse Width Modulator |
| 中文描述： | 調(diào)節(jié)脈沖寬度調(diào)制器 |
| 文件頁數(shù)： | 9/22頁 |
| 文件大?。?/td> | 1172K |
| 代理商： | LM3524D |
Functional Description
(Continued)
The output of the amplifier, or input to the pulse width modu-
lator, can be overridden easily as its output impedance is
very high (Z
.
5 M
). For this reason a DC voltage can be
applied to pin 9 which will override the error amplifier and
force a particular duty cycle to the outputs. An example of
this could be a non-regulating motor speed control where a
variable voltage was applied to pin 9 to control motor speed.
A graph of the output duty cycle vs the voltage on pin 9 is
shown in
Figure 5
.
The duty cycle is calculated as the percentage ratio of each
output’s ON-time to the oscillator period. Paralleling the out-
puts doubles the observed duty cycle.
The amplifier’s inputs have a common-mode input range of
1.5V–5.5V. The on board regulator is useful for biasing the
inputs to within this range.
CURRENT LIMITING
The function of the current limit amplifier is to override the
error amplifier’s output and take control of the pulse width.
The output duty cycle drops to about 25% when a current
limit sense voltage of 200 mV is applied between the +C
L
and C
sense terminals. Increasing the sense voltage ap-
proximately 5% results in a 0% output duty cycle. Care
should be taken to ensure the 0.7V to +1.0V input common-
mode range is not exceeded.
In most applications, the current limit sense voltage is pro-
duced by a current through a sense resistor. The accuracy of
this measurement is limited by the accuracy of the sense
resistor, and by a small offset current, typically 100 μA,
flowing from +CL to CL.
OUTPUT STAGES
The outputs of the LM3524D are NPN transistors, capable of
a maximum current of 200 mA. These transistors are driven
180 out of phase and have non-committed open collectors
and emitters as shown in
Figure 6
.
00865008
FIGURE 5.
00865009
FIGURE 6.
L
www.national.com
9
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM3524DM | 功能描述:電壓模式 PWM 控制器 RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| LM3524DM/NOPB | 功能描述:電壓模式 PWM 控制器 REGULATING PULSE WIDTH MODULATOR RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| LM3524DM/NOPB | 制造商:Texas Instruments 功能描述:Pulse Width Modulation (PWM) Controller |
| LM3524DMX | 功能描述:電壓模式 PWM 控制器 RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| LM3524DMX/NOPB | 功能描述:電壓模式 PWM 控制器 RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
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