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參數資料
| 型號： | LM5008MMXEP |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 0.61 A SWITCHING REGULATOR, 600 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | PLASTIC, MSOP-8 |
| 文件頁數： | 13/15頁 |
| 文件大小： | 662K |
| 代理商： | LM5008MMXEP |
Typical Performance
Characteristics (Continued)
Functional Description
The LM5008EP 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 LM5008EP is shown in Figure 1.
The LM5008EP 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
CC 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 LM5008EP is a Buck DC-DC regulator that uses a
control scheme in which the on-time varies inversely with
line voltage (V
IN). 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
ON). Following the ON period the switch will re-
main 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 LM5008EP 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
20187623
FIGURE 6. Efficiency vs V
IN
(Circuit of Figure 13)
20187627
FIGURE 7. Efficiency vs Load Current vs V
IN
(Circuit of Figure 13)
20187624
FIGURE 8. Output Voltage vs Load Current
(Circuit of Figure 13)
LM5008EP
www.national.com
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相關代理商/技術參數 |
參數描述 |
|---|---|
| LM5008SD | 功能描述:直流/直流開關轉換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| LM5008SD/NOPB | 功能描述:直流/直流開關轉換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| LM5008SDC | 功能描述:直流/直流開關轉換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| LM5008SDC/NOPB | 功能描述:直流/直流開關轉換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| LM5008SDCX | 功能描述:直流/直流開關轉換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
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