- 您现在的位置：买卖IC网 > PDF目录224108 > LM5009SD (NATIONAL SEMICONDUCTOR CORP) 150 mA, 100V Step-Down Switching Regulator PDF资料下载
参数资料
| 型号： | LM5009SD |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 150 mA, 100V Step-Down Switching Regulator |
| 中文描述： | 0.37 A SWITCHING REGULATOR, DSO8 |
| 封装： | 4 X 4 MM, EXPOSED PAD, LLP-8 |
| 文件页数： | 12/14页 |
| 文件大小： | 647K |
| 代理商： | LM5009SD |
Typical Application Circuit and Block Diagram
Functional Description
The LM5009 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 LM5009 is shown in Figure 1.
The LM5009 can be applied in numerous applications to
efficiently regulate down higher voltages. This regulator is
well suited for 48 Volt Telecom and the 42V Automotive
power bus ranges. Additional 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 LM5009 is a Buck DC-DC regulator that uses a control
scheme in which the on-time varies inversely with line volt-
age (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 remain off for
at least the minimum off-timer period of 300 ns. 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, at which time the off-time increases based on
the required duty cycle.
The LM5009 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
the end of the off-time. The next on-time period starts when
the voltage at FB falls below the internal reference - until
then the inductor current remains zero. In this mode the
operating frequency is lower than in continuous conduction
mode, and varies with load current. Therefore at light loads
the conversion efficiency is maintained, since the switching
losses reduce with the reduction in load and frequency. The
discontinuous operating frequency can be calculated as fol-
lows:
where R
L = the load resistance
In continuous conduction mode, current flows continuously
through the inductor and never ramps down to zero. In this
mode the operating frequency is greater than the discontinu-
ous mode frequency and remains relatively constant with
load and line variations. The approximate continuous mode
operating frequency can be calculated as follows:
20165801
FIGURE 1.
LM5009
www.national.com
7
相关PDF资料 |
PDF描述 |
|---|---|
| LM5009SDX | 150 mA, 100V Step-Down Switching Regulator |
| LMK02000 | Precision Clock Conditioner with Integrated PLL |
| LMR-01-Z | SPECIAL SWITCH-JOYSTICK SWITCH, SPDT, MOMENTARY, 1A, 14VDC, PANEL MOUNT |
| LMR-011 | SPECIAL SWITCH-JOYSTICK SWITCH, SPDT, MOMENTARY, 1A, 14VDC, PANEL MOUNT |
| LMR-012 | SPECIAL SWITCH-JOYSTICK SWITCH, SPDT, MOMENTARY, 1A, 14VDC, PANEL MOUNT |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LM5009SDC | 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 |
| LM5009SDC/NOPB | 功能描述:直流/直流开关转换器 150 MA 100V STEP-DWN SWITCHING REG 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 |
| LM5009SDC/NOPB | 制造商:Texas Instruments 功能描述:DC/DC Converter IC |
| LM5009SDCNOPB | 制造商:NATIONAL 功能描述:Pb Free |
| LM5009SDCX | 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 |
发布紧急采购，3分钟左右您将得到回复。