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参数资料
| 型号： | 750105 |
| 厂商： | Wurth Electronics Inc |
| 文件页数： | 16/24页 |
| 文件大小： | 0K |
| 描述： | BOARD EVAL FOR LT3574 |
| 标准包装： | 1 |
| 主要目的： | DC/DC，步降 |
| 输出及类型： | 1，隔离 |
| 功率 - 输出： | 2.5W |
| 输出电压： | 5V |
| 电流 - 输出： | 500mA（最小值） |
| 输入电压： | 10 ~ 30 V |
| 稳压器拓扑结构： | 回扫 |
| 板类型： | 完全填充 |
| 已供物品： | 板 |
| 已用 IC / 零件： | LT3574 |
| 其它名称： | 732-3309 |
LT3574
APPLICATIONS INFORMATION
BIAS winding turns ratio is selected to program the BIAS
voltage to 3~5V. The BIAS voltage shall not exceed the
input voltage.
The turns ratio is then selected as primary: secondary:
BIAS = 3:1:1.
2. Select the transformer primary inductance for target
switching frequency.
The LT3574 requires a minimum amount of time to sample
the output voltage during the off-time. This off-time,
t OFF(MIN) , shall be greater than 350ns over all operating
conditions. The converter also has a minimum current limit,
I MIN , of 175mA to help create this off-time. This defines
the minimum required inductance as defined as:
In this design example, the minimum primary inductance is
used to achieve a nominal switching frequency of 350kHz
at full load. The PA2627NL from Pulse Engineering is
chosen as the flyback transformer.
Given the turns ratio and primary inductance, a custom-
ized transformer can be designed by magnetic component
manufacturer or a multi-winding transformer such as a
Coiltronics Versa-Pac may be used.
3. Select the output diodes and output capacitor.
The output diode voltage stress V D is the summation of
the output voltage and reflection of input voltage to the
secondary side. The average diode current is the load
current.
L MIN =
N( V OUT + V F )
I MIN
? t OFF ( MIN )
V D = V OUT +
V IN
N
f SW =
=
t ON + t OFF I PK I PK
+ V
V IN
N PS OUT F )
+
LI 2 PK
D V MAX =
The transformer primary inductance also affects the
switching frequency which is related to the output ripple. If
above the minimum inductance, the transformer’s primary
inductance may be selected for a target switching frequency
range in order to minimize the output ripple.
The following equation estimates the switching frequency.
1 1
( V
L L
Table 7. Switching Frequency at Different Primary Inductance
at I PK
f SW AT V IN(MIN) f SW AT V IN(MAX)
L (μH) (kHz) (kHz)
30 317 373
60 159 187
The output capacitor should be chosen to minimize the
output voltage ripple while considering the increase in
size and cost of a larger capacitor. The following equation
calculates the output voltage ripple.
2 CV OUT
4. Select the snubber circuit to clamp the switch voltage
spike.
A flyback converter generates a voltage spike during switch
turn-off due to the leakage inductance of the transformer.
In order to clamp the voltage spike below the maximum
rating of the switch, a snubber circuit is used. There are
many types of snubber circuits, for example R-C, R-C-D and
Zener clamps. Among them, RCD is widely used. Figure 9
shows the RCD snubber in a flyback converter.
120
79
93
A typical switch node waveform is shown in Figure 10.
Note: The switching frequency is calculated at maximum output.
3574f
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相关代理商/技术参数 |
参数描述 |
|---|---|
| 75010531 | 制造商:PHILIPS 功能描述:STARTER FLUORESCENT TUBE 70-125W 制造商:Philco/Philips 功能描述:STARTER, FLUORESCENT TUBE, 70-125W 制造商:NXP Semiconductors 功能描述:STARTER, FLUORESCENT TUBE, 70-125W; Accessory Type:Starter; For Use With:Fluorescent; SVHC:No SVHC (18-Jun-2012); Power Rating:125W; Supply Voltage:240V ;RoHS Compliant: Yes |
| 750-105-R220/270 | 制造商:CTS Corporation 功能描述: |
| 750-105-R220/330 | 制造商: 功能描述: 制造商:undefined 功能描述: 制造商:CTS Corporation 功能描述:S10-R220/330 |
| 750106 | 功能描述:BOARD EVAL FOR LT3575 RoHS:是 类别:编程器，开发系统 >> 评估板 - DC/DC 与 AC/DC（离线）SMPS 系列:- 标准包装:1 系列:- 主要目的:DC/DC，步降 输出及类型:1，非隔离 功率 - 输出:- 输出电压:3.3V 电流 - 输出:3A 输入电压:4.5 V ~ 28 V 稳压器拓扑结构:降压 频率 - 开关:250kHz 板类型:完全填充 已供物品:板 已用 IC / 零件:L7981 其它名称:497-12113STEVAL-ISA094V1-ND |
| 750-106 | 制造商:GLENAIR 制造商全称:Glenair, Inc. 功能描述:Pre-Terminated Assemblies |
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