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参数资料
| 型号： | LM5000-3MTCX/NOPB |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 2.7 A SWITCHING REGULATOR, 840 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封装： | TSSOP-16 |
| 文件页数： | 18/18页 |
| 文件大小： | 388K |
| 代理商： | LM5000-3MTCX/NOPB |
Block Diagram
20031903
Boost Regulator Operation
The LM5000 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 de-
crease with smaller. This voltage is compared with the sum-
mation of the SW volatge and the ramp compensation.The
ramp compensation is used in PWM architectures to eliminate
the sub-harmonic oscillations that occur during duty cycles
greater than 50%. Once the summation of the ramp compen-
sation 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 LM5000 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 tem-
perature reaches excessive levels. The UVP comparator pro-
tects 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 pre-
vent the output voltage from rising at no loads allowing full
PWM operation over all load conditions. The LM5000 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 10A current source.
The LM5000 is available in two operating frequency ranges.
The LM5000-3 is pin selectable for either 300kHz (FS
Grounded) or 700kHz (FS Open). The LM5000-6 is pin se-
lectable for either 600kHz (FS Grounded) or 1.3MHz (FS
Open)
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www.national.com
LM5000
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参数描述 |
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| LM5000-3MYC | 制造商:Texas Instruments 功能描述: |
| LM5000EP | 制造商:NSC 制造商全称:National Semiconductor 功能描述:Enhanced Plastic High Voltage Switch Mode Regulator |
| LM5000EVAL | 功能描述:电源管理IC开发工具 LM5000 EVAL UNIT RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| LM5000EVAL/NOPB | 功能描述:EVALUATION BOARD FOR LM5000 RoHS:是 类别:编程器，开发系统 >> 评估板 - DC/DC 与 AC/DC（离线）SMPS 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:True Shutdown™ 主要目的:DC/DC，步升 输出及类型:1，非隔离 功率 - 输出:- 输出电压:- 电流 - 输出:1A 输入电压:2.5 V ~ 5.5 V 稳压器拓扑结构:升压 频率 - 开关:3MHz 板类型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
| LM5000SD-3 | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
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