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參數(shù)資料
| 型號： | LM5008 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | High Voltage (100V) Step Down Switching Regulator |
| 中文描述： | 高電壓（100V的）降壓開關(guān)穩(wěn)壓器 |
| 文件頁數(shù)： | 7/15頁 |
| 文件大小： | 278K |
| 代理商： | LM5008 |
Typical Performance
Characteristics
(Continued)
Functional Description
The LM5008 Step Down Switching Regulator features all the
functions needed to implement a low cost, efficient, Buck
bias power converter. This high voltage regulator contains a
100 V N-Channel Buck Switch, is easy to implement and is
provided in the MSOP-8 and the thermally enhanced LLP-8
packages. The regulator is based on a hysteretic control
scheme using an on-time inversely proportional to V
IN
. The
hysteretic control requires no loop compensation. Current
limit is implemented with forced off-time, which is inversely
proportional to V
OUT
. This scheme ensures short circuit pro-
tection while providing minimum foldback. The Functional
Block Diagram of the LM5008 is shown in
Figure 1
.
The LM5008 can be applied in numerous applications to
efficiently regulate down higher voltages. This regulator is
well suited for 48 Volt Telecom and the new 42V Automotive
power bus ranges. Protection features include: Thermal
Shutdown, V
under-voltage lockout, Gate drive under-
voltage lockout, Max Duty Cycle limit timer and the intelligent
current limit off timer.
Hysteretic Control Circuit
Overview
The LM5008 is a Buck DC-DC regulator that uses a control
scheme in which the on-time varies inversely with line volt-
age (V
). Control is based on a comparator and the on-time
one-shot, with the output voltage feedback (FB) compared to
an internal reference (2.5V). If the FB level is below the
reference the buck switch is turned on for a fixed time
determined by the line voltage and a programming resistor
(R
). Following the ON period the switch will remain off for
at least the minimum off-timer period of 300ns. If FB is still
below the reference at that time the switch will turn on again
for another on-time period. This will continue until regulation
is achieved.
The LM5008 operates in discontinuous conduction mode at
light load currents, and continuous conduction mode at
heavy load current. In discontinuous conduction mode, cur-
rent through the output inductor starts at zero and ramps up
to a peak during the on-time, then ramps back to zero before
20097923
FIGURE 6. Efficiency vs V
IN
(Circuit of
Figure 13
)
20097927
FIGURE 7. Efficiency vs Load Current vs V
IN
(Circuit of
Figure 13
)
20097924
FIGURE 8. Output Voltage vs Load Current
(Circuit of
Figure 13
)
L
www.national.com
7
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM5008_09 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:High Voltage (100V) Step Down Switching Regulator |
| LM5008A | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:100V, 350 mA Constant On-Time Buck Switching Regulator |
| LM5008AEVAL/NOPB | 功能描述:電源管理IC開發(fā)工具 LM5008A EVAL BOARD RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| LM5008AMM | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:100V, 350 mA Constant On-Time Buck Switching Regulator |
| LM5008AMM/NOPB | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 100V,350Ma Buck Reg RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
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