参数资料
| 型号： | NCP5422ADR2 |
| 厂商： | ON Semiconductor |
| 文件页数： | 10/16页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM 16-SOIC |
| 产品变化通告： | Product Obsolescence 11/Feb/2009 |
| 标准包装： | 2,500 |
| PWM 型： | 电流/电压模式，V²? |
| 输出数： | 1 |
| 频率 - 最大： | 750kHz |
| 占空比： | 100% |
| 电源电压： | 10.8 V ~ 13.2 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | 0°C ~ 70°C |
| 封装/外壳： | 16-SOIC（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
| 其它名称： | NCP5422ADR2OS |
NCP5422A
(VIN(MIN) * VOUT) VOUT
LMIN +
Selecting the Switching Frequency
Selecting the switching frequency is a trade-off between
component size and power losses. Operation at higher
switching frequencies allows the use of smaller inductor and
capacitor values. Nevertheless, it is common to select lower
frequency operation because a higher frequency results in
lower efficiency due to MOSFET gate charge losses.
Additionally, the use of smaller inductors at higher
frequencies results in higher ripple current, higher output
voltage ripple, and lower efficiency at light load currents.
The value of the oscillator resistor is designed to be
linearly related to the switching period. If the designer
prefers not to use Figure 8 to select the necessary resistor, the
The minimum value of inductance which prevents
inductor saturation or exceeding the rated FET current can
be calculated as follows:
fSW VIN(MIN) ISW(MAX)
where:
L MIN = minimum inductance value;
V IN(MIN) = minimum design input voltage;
V OUT = output voltage;
f SW = switching frequency;
I SW(MAX) - maximum design switch current.
The inductor ripple current can then be determined:
D IL + OUT
following equation quite accurately predicts the proper
resistance for room temperature conditions.
V
L
(1 * D)
fSW
ROSC +
21700 * fSW
2.31 fSW
where:
D I L = inductor ripple current;
where:
R OSC = oscillator resistor in k W ;
f SW = switching frequency in kHz.
800
700
600
V OUT = output voltage;
L = inductor value;
D = duty cycle.
f SW = switching frequency
The designer can now verify if the number of output
capacitors will provide an acceptable output voltage ripple
(1.0% of output voltage is common). The formula below is
used:
500
400
D IL +
Rearranging we have:
D VOUT
ESRMAX
300
200
where:
ESRMAX +
D VOUT
D IL
100
10
20
30
40
50
60
ESR MAX = maximum allowable ESR;
D V OUT = 1.0% × V OUT = maximum allowable output
R OSC (k W )
Figure 8. Switching Frequency
Selection of the Output Inductor
voltage ripple ( budgeted by the designer );
D I L = inductor ripple current;
V OUT = output voltage.
The number of output capacitors is determined by:
The inductor should be selected based on its inductance,
current capability, and DC resistance. Increasing the
Number of capacitors +
ESRCAP
ESRMAX
IL(PEAK) + IOUT )
IL(VALLEY) + IOUT *
inductor value will decrease output voltage ripple, but
degrade transient response. There are many factors to
consider in selecting the inductor including cost, efficiency,
EMI and ease of manufacture. The inductor must be able to
handle the peak current at the switching frequency without
saturating, and the copper resistance in the winding should
be kept as low as possible to minimize resistive power loss.
There are a variety of materials and types of magnetic
cores that could be used for this application. Among them
are ferrites, molypermalloy cores (MPP), amorphous and
powdered iron cores. Powdered iron cores are very
commonly used. Powdered iron cores are very suitable due
to its high saturation flux density and have low loss at high
frequencies, a distributed gap and exhibit very low EMI.
where:
ESR CAP = maximum ESR per capacitor (specified in
manufacturer's data sheet).
The designer must also verify that the inductor value
yields reasonable inductor peak and valley currents (the
inductor current is a triangular waveform):
D IL
2
where:
I L(PEAK) = inductor peak current;
I OUT = load current;
D I L = inductor ripple current.
D IL
2
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10
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| NCP5422ADR2G | 功能描述:DC/DC 开关控制器 Dual Out-Of-Phase Synchronous Buck RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
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