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参数资料
| 型号： | LM5007MMEP |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING REGULATOR, PDSO8 |
| 封装： | PLASTIC, MSOP-8 |
| 文件页数： | 9/12页 |
| 文件大小： | 231K |
| 代理商： | LM5007MMEP |
Hysteretic Control Circuit
Overview (Continued)
The output voltage (Vout) can be programmed by two exter-
nal resistors as shown in Figure 1. The regulation point can
be calculated as follows:
V
OUT =2.5x(R1+R2)/R2
The feedback comparator in hysteretic regulators depend
upon the output ripple voltage to switch the output transistor
on and off at regular intervals. In order for the internal
comparator to respond quickly to changes in output voltage,
proportional to inductor current, a minimum amount of ca-
pacitor Equivalent Series Resistance (ESR) is required. A
ripple voltage of 25mV to 50mV is recommended at the
feedback pin (FB) for stable operation. In cases where the
intrinsic capacitor ESR is too small, additional series resis-
tance may be added.
For applications where lower output voltage ripple is re-
quired the load can be connected directly to the low ESR
output capacitor, as shown in Figure 1. The series resistor
(R) will degrade the load regulation. Another technique for
enhancing the ripple voltage at the FB pin is to place a
capacitor in parallel with the feedback divider resistor R1.
The addition of the capacitor reduces the attenuation of the
ripple voltage from the feedback divider
High Voltage Bias Regulator
The LM5007EP contains an internal high voltage bias regu-
lator. The input pin (Vin) can be connected directly to line
voltages from 9 to 75 Volts. The regulator is internally current
limited to 10mA. Upon power up, the regulator is enabled
and sources current into an external capacitor connected to
the Vcc pin. When the voltage on the Vcc pin reaches the
regulation point of 7V, the controller output is enabled.
An external auxiliary supply voltage can be applied to the
Vcc pin. If the auxiliary voltage is greater than 7 Volts the
internal regulator will essentially shutoff, thus reducing inter-
nal power dissipation.
20093905
FIGURE 1. Low Ripple Output Configuration
LM5007EP
Enhanced
Plastic
www.national.com
6
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM5007MMX | 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 |
| LM5007MMX/NOPB | 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 |
| LM5007MMXNOPB | 制造商:National Semiconductor 功能描述:Conv DC-DC Single Step Down 9V to 75V 8-Pin MSOP T/R |
| LM5007SD | 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 |
| LM5007SD/NOPB | 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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