- 您现在的位置：买卖IC网 > PDF目录17233 > NCP5424EVB (ON Semiconductor)EVAL BOARD FOR NCP5424 PDF资料下载
参数资料
| 型号： | NCP5424EVB |
| 厂商： | ON Semiconductor |
| 文件页数： | 10/18页 |
| 文件大小： | 0K |
| 描述： | EVAL BOARD FOR NCP5424 |
| 产品变化通告： | Product Obsolescence 24/Jan/2011 |
| 设计资源： | NCP5424 Demo Board BOM NCP5424EVB Gerber Files NCP5424EVB Schematic |
| 标准包装： | 1 |
| 主要目的： | DC/DC，步降 |
| 输出及类型： | 1，非隔离 |
| 输出电压： | 1.5V |
| 电流 - 输出： | 17A |
| 输入电压： | 3.3V，5V，12V |
| 稳压器拓扑结构： | 降压 |
| 频率 - 开关： | 300kHz |
| 板类型： | 完全填充 |
| 已供物品： | 板 |
| 已用 IC / 零件： | NCP5424 |
| 其它名称： | NCP5424EVBOS |
NCP5424
DESIGN GUIDELINES
Definition of the design specifications
The output voltage tolerance can be affected by any or all
of the following:
1. buck regulator output voltage setpoint accuracy;
2. output voltage change due to discharging or charging
of the bulk decoupling capacitors during a load
current transient;
3. output voltage change due to the ESR and ESL of the
bulk and high frequency decoupling capacitors,
circuit traces, and vias;
4. output voltage ripple and noise.
Budgeting the tolerance is left to the designer who must
consider all of the above effects and provide an output
voltage that will meet the specified tolerance at the load.
The designer must also ensure that the regulator
component temperatures are kept within the manufacturer ’s
specified ratings at full load and maximum ambient
temperature.
V L = output inductor voltage drop due to inductor wire
DC resistance;
V IN = buck regulator input voltage;
V LFET = low side FET voltage drop due to R DS(ON) .
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
following equation quite accurately predicts the proper
resistance for room temperature conditions.
Selecting Feedback Divider Resistors
ROSC +
21700 * fSW
2.31fSW
V OUT
R1
V FB
R2
Figure 7. Selecting Feedback Divider Resistors
The feedback pins (V FB1(2) ) are connected to external
resistor dividers to set the output voltages. The error
amplifier is referenced to 1.0 V and the output voltage is
determined by selecting resistor divider values. Resistor R1
is selected based on a design trade?off between efficiency
where:
R OSC = oscillator resistor in k W ;
f SW = switching frequency in kHz.
800
700
600
500
400
300
200
100
and output voltage accuracy. The output voltage error can be
10
20
30
40
50
60
Error% + 1
10 * 6 R1
estimated due to the bias current of the error amplifier
neglecting resistor tolerance:
100%
1
R2 can be sized after R1 has been determined:
R OSC (k W )
Figure 8. Switching Frequency
Selection of the Output Inductor
The inductor should be selected based on its inductance,
current capability, and DC resistance. Increasing the
R2 + R1
VOUT
1
* 1
inductor value will decrease output voltage ripple, but
degrade transient response. There are many factors to
VOUT ) (VHFET ) VL)
VIN ) VLFET * VHFET * VL
Calculating Duty Cycle
The duty cycle of a buck converter (including parasitic
losses) is given by the formula:
Duty Cycle + D +
where:
V OUT = buck regulator output voltage;
V HFET = high side FET voltage drop due to R DS(ON) ;
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
http://onsemi.com
10
相关PDF资料 |
PDF描述 |
|---|---|
| BRL3225T6R8M | INDUCTOR 6.8UH 20% 1210 SMD |
| GBC13DRTI | CONN EDGECARD 26POS DIP .100 SLD |
| RCM06DCCT | CONN EDGECARD 12POS R/A .156 SLD |
| BRL3225T330K | INDUCTOR 33UH 10% 1210 SMD |
| GBC06DRTF | CONN EDGECARD 12POS DIP .100 SLD |
相关代理商/技术参数 |
参数描述 |
|---|---|
| NCP5425 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:Dual Synchronous Buck Controller |
| NCP5425/D | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Dual Synchronous Buck Controller |
| NCP5425_06 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:Dual Synchronous Buck Controller |
| NCP5425DB | 功能描述:DC/DC 开关控制器 Dual Synchronous 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 |
| NCP5425DBG | 功能描述:DC/DC 开关控制器 Dual 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 |
发布紧急采购，3分钟左右您将得到回复。