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參數(shù)資料
| 型號(hào)： | LM3478MM |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | High Efficiency Low-Side N-Channel Controller for Switching Regulator |
| 中文描述： | 1 A SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | MSOP-8 |
| 文件頁數(shù)： | 13/21頁 |
| 文件大?。?/td> | 624K |
| 代理商： | LM3478MM |
Functional Description
(Continued)
SHORT-CIRCUIT PROTECTION
When the voltage across the sense resistor (measured on
I
Pin) exceeds 350mV, short-circuit current limit gets
activated. A comparator inside LM3478 reduces the switch-
ing frequency by a factor of 5 and maintains this condition till
the short is removed.
Typical Applications
The LM3478 may be operated in either continuous or dis-
continuous conduction mode. The following applications are
designed for continuous conduction operation. This mode of
operation has higher efficiency and lower EMI characteristics
than the discontinuous mode.
BOOST CONVERTER
The most common topology for LM3478 is the boost or
step-up topology. The boost converter converts a low input
voltage into a higher output voltage. The basic configuration
for a boost regulator is shown in
Figure 8
. In continuous
conduction mode (when the inductor current never reaches
zero at steady state), the boost regulator operates in two
cycles. In the first cycle of operation, MOSFET Q is turned
on and energy is stored in the inductor. During this cycle,
diode D is reverse biased and load current is supplied by the
output capacitor, C
OUT
.
In the second cycle, MOSFET Q is off and the diode is
forward biased. The energy stored in the inductor is trans-
ferred to the load and output capacitor. The ratio of these two
cycles determines the output voltage. The output voltage is
defined as:
(ignoring the drop across the MOSFET and the diode), or
where D is the duty cycle of the switch, V
D
is the forward
voltage drop of the diode, and V
Q
is the drop across the
MOSFET when it is on. The following sections describe
selection of components for a boost converter
10135514
FIGURE 6. Frequency Adjust
10135516
FIGURE 7. Shutdown Operation in Frequency Adjust Mode
L
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM3478MM/E7001794 | 制造商:Texas Instruments 功能描述: |
| LM3478MM/NOPB | 功能描述:DC/DC 開關(guān)控制器 HI EFF LOW-SIDE N CH CONTROLLER RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| LM3478MM/NOPB | 制造商:Texas Instruments 功能描述:Pulse Width Modulation (PWM) Controller |
| LM3478MMX | 功能描述:DC/DC 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| LM3478MMX/HALF | 制造商:Texas Instruments 功能描述: |
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