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參數(shù)資料
| 型號： | LM5000 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | High Voltage Switch Mode Regulator |
| 中文描述： | 高壓開關模式穩(wěn)壓器 |
| 文件頁數(shù)： | 10/18頁 |
| 文件大小： | 438K |
| 代理商： | LM5000 |
Block Diagram
20098303
Boost Regulator Operation
The LM5000EP utilizes a PWM control scheme to regulate
the output voltage over all load conditions. The operation
can best be understood referring to the block diagram and
Figure 3
. At the start of each cycle, the oscillator sets the
driver logic and turns on the NMOS power device conducting
current through the inductor, cycle 1 of
Figure 3
(a). During
this cycle, the voltage at the COMP pin controls the peak
inductor current. The COMP voltage will increase with larger
loads and decrease with smaller. This voltage is compared
with the summation of the SW volatge and the ramp com-
pensation.The ramp compensation is used in PWM architec-
tures to eliminate the sub-harmonic oscillations that occur
during duty cycles greater than 50%. Once the summation of
the ramp compensation and switch voltage equals the
COMP voltage, the PWM comparator resets the driver logic
turning off the NMOS power device. The inductor current
then flows through the output diode to the load and output
capacitor, cycle 2 of
Figure 3
(b). The NMOS power device is
then set by the oscillator at the end of the period and current
flows through the inductor once again.
The LM5000EP has dedicated protection circuitry running
during the normal operation to protect the IC. The Thermal
Shutdown circuitry turns off the NMOS power device when
the die temperature reaches excessive levels. The UVP
comparator protects the NMOS power device during supply
power startup and shutdown to prevent operation at voltages
less than the minimum input voltage. The OVP comparator is
used to prevent the output voltage from rising at no loads
allowing full PWM operation over all load conditions. The
LM5000EP also features a shutdown mode. An external
capacitor sets the softstart time by limiting the error amp
output range, as the capacitor charges up via an internal
10μA current source.
The LM5000EP is available in two operating frequency
ranges. The LM5000-3EP is pin selectable for either 300kHz
(FS Grounded) or 700kHz (FS Open). The LM5000-6EP is
pin selectable for either 600kHz (FS Grounded) or 1.3MHz
(FS Open)
L
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LM5000_07 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:High Voltage Switch Mode Regulator |
| LM5000-3MTC | 功能描述:直流/直流開關轉(zhuǎn)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(shù)量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| LM5000-3MTC | 制造商:Texas Instruments 功能描述:SWITCH MODE REG SMD 5000 TSSOP16 |
| LM5000-3MTC/NOPB | 功能描述:直流/直流開關轉(zhuǎn)換器 High Vltg Switch Mode Reg 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(shù)量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| LM5000-3MTCEP | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Enhanced Plastic High Voltage Switch Mode Regulator |
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