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| 型号： | NCV51411DR2G |
| 厂商： | ON Semiconductor |
| 文件页数： | 9/16页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK 1.5A 8SOIC |
| 标准包装： | 1 |
| 类型： | 降压（降压） |
| 输出数： | 1 |
| 输入电压： | 4.5 V ~ 40 V |
| PWM 型： | 混合物 |
| 频率 - 开关： | 260kHz |
| 电流 - 输出： | 1.5A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 剪切带 (CT) |
| 供应商设备封装： | 8-SOICN |
| 其它名称： | NCV51411DR2GOSCT |
NCV51411
C COMP = Compensation capacitor connected to the V C pin
I SOURCE = Output Source Current of the error amplifier.
Using a 0.1 m F C COMP , the calculation shows a T SS over
5.0 ms which is adequate to avoid any current stresses.
Figure 9 shows the gradual rise of the V C , V O and envelope
of the V SW during power up. There is no voltage over ? shoot
after the output voltage reaches the regulation. If the supply
voltage rises slower than the V C pin, output voltage may
over ? shoot.
Figure 10. In Short Circuit, the Foldback Current and
Foldback Frequency Limit the Switching Current to
Protect the IC, Inductor and Catch Diode
Thermal Considerations
A calculation of the power dissipation of the IC is always
necessary prior to the adoption of the regulator. The current
drawn by the IC includes quiescent current, pre ? driver
current, and power switch base current. The quiescent
current drives the low power circuits in the IC, which
Figure 9. The Power Up Transition of NCV51411
Regulator
include comparators, error amplifier and other logic blocks.
Therefore, this current is independent of the switching
current and generates power equal to
Short Circuit
WQ + VIN
IQ
(VIN * VO ) O )
VIN
When the V FB pin voltage drops below Foldback
Threshold, the regulator reduces the peak current limit by
40% and switching frequency to 1/4 of the nominal
frequency. These features are designed to protect the IC and
external components during over load or short circuit
conditions. In those conditions, peak switching current is
clamped to the current limit threshold. The reduced
switching frequency significantly increases the ripple
current, and thus lowers the DC current. The short circuit can
cause the minimum duty cycle to be limited by Minimum
Output Pulse Width. The foldback frequency reduces the
minimum duty cycle by extending the switching cycle. This
protects the IC from overheating, and also limits the power
that can be transferred to the output. The current limit
foldback effectively reduces the current stress on the
inductor and diode. When the output is shorted, the DC
current of the inductor and diode can approach the current
limit threshold. Therefore, reducing the current limit by 40%
can result in an equal percentage drop of the inductor and
diode current. The short circuit waveforms are captured in
Figure 10, and the benefit of the foldback frequency and
where:
I Q = quiescent current.
The pre ? driver current is used to turn on/off the power
switch and is approximately equal to 12 mA in worst case.
During steady state operation, the IC draws this current from
the Boost pin when the power switch is on and then receives
it from the V IN pin when the switch is off. The pre ? driver
current always returns to the V SW pin. Since the pre ? driver
current goes out to the regulator ’s output even when the
power switch is turned off, a minimum load is required to
prevent overvoltage in light load conditions. If the Boost pin
voltage is equal to V IN + V O when the switch is on, the power
dissipation due to pre ? driver current can be calculated by
V 2
WDRV + 12 mA
The base current of a bipolar transistor is equal to collector
current divided by beta of the device. Beta of 60 is used here
to estimate the base current. The Boost pin provides the base
current when the transistor needs to be on. The power
dissipated by the IC due to this current is
current limit is self ? evident.
http://onsemi.com
9
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相关代理商/技术参数 |
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|---|---|
| NCV51411MNR2 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:1.5 A, 260 kHz, Low Voltage Buck Regulator with Synchronization Capability |
| NCV51411MNR2G | 功能描述:直流/直流开关转换器 BUCK REGULATOR 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 |
| NCV51411PWR2 | 功能描述:直流/直流开关转换器 1.5A Low Voltage 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 |
| NCV51411PWR2G | 功能描述:直流/直流开关转换器 1.5A Low Voltage Buck 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 |
| NCV5171 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:1.5 A 280 kHz Boost Regulators |
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