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| 型号： | LT3757EDD#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 19/36页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST FLYBK INV 10DFN |
| 产品培训模块： | LT3757 and LT3758 - Boost, Flyback, SEPIC and Inverting Controllers |
| 特色产品： | LT3757 - Inverting Controller |
| 标准包装： | 121 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 1MHz |
| 电源电压： | 2.9 V ~ 40 V |
| 降压： | 无 |
| 升压： | 是 |
| 回扫： | 是 |
| 反相： | 是 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 封装/外壳： | 10-WFDFN 裸露焊盘 |
| 包装： | 管件 |
| 产品目录页面： | 1332 (CN2011-ZH PDF) |
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LT3757/LT3757A
APPLICATIONS INFORMATION
I LP(MAX) = I SW(MAX) =
D 2MAX ? V 2IN(MIN) ? h
L P =
D2 2 ? (V OUT + V D )
L S =
I LS(MAX) = I D(MAX) =
I LP(RMS) = 2 ? I LP(MAX) ?
I LS(RMS) = 2 ? I LS(MAX) ?
N P L P
N S
L S
V 2SN ? V SN ? V OUT ?
R SN = 2 ?
FlybackConverter:TransformerDesignfor
Discontinuous Mode Operation
The transformer design for discontinuous mode of opera-
tion is chosen as presented here. According to Figure 8,
the minimum D3 (D3 MIN ) occurs when the converter
has the minimum V IN and the maximum output power
(P OUT ). Choose D3 MIN to be equal to or higher than 10%
to guarantee the converter is always in discontinuous
mode operation (choosing higher D3 allows the use of low
inductances, but results in a higher switch peak current).
The user can choose a D MAX as the start point. Then, the
maximum average primary currents can be calculated by
the following equation:
P OUT(MAX)
D MAX ? V IN(MIN) ? h
where h is the converter efficiency.
If the flyback converter has multiple outputs, P OUT(MAX)
is the sum of all the output power.
The maximum average secondary current is:
I OUT(MAX)
D2
where:
D2 = 1 – D MAX – D3
the primary and secondary RMS currents are:
D MAX
3
D2
3
According to Figure 8, the primary and secondary peak
currents are:
I LP(PEAK) = I SW(PEAK) = 2 ? I LP(MAX)
I LS(PEAK) = I D(PEAK) = 2 ? I LS(MAX)
The primary and second inductor values of the flyback
converter transformer can be determined using the fol-
lowing equations:
2 ? P OUT(MAX) ? f
2 ? I OUT(MAX) ? f
The primary to second turns ratio is:
=
Flyback Converter: Snubber Design
Transformer leakage inductance (on either the primary or
secondary) causes a voltage spike to occur after the MOS-
FET turn-off. This is increasingly prominent at higher load
currents, where more stored energy must be dissipated.
In some cases a snubber circuit will be required to avoid
overvoltage breakdown at the MOSFET’s drain node. There
are different snubber circuits, and Application Note 19 is
a good reference on snubber design. An RCD snubber is
shown in Figure 7.
The snubber resistor value (R SN ) can be calculated by the
following equation:
N P
N S
I 2SW(PEAK) ? L LK ? f
3757afd
19
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3757EDD-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Boost, Flyback, SEPIC and Inverting Controller |
| LT3757EMSE | 制造商:LINER 制造商全称:Linear Technology 功能描述:Boost, Flyback, SEPIC and Inverting Controller |
| LT3757EMSE#PBF | 功能描述:IC REG CTRLR PWM CM 10-MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 特色产品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 标准包装:1 系列:PowerWise® PWM 型:电压模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.5 V ~ 18 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:-5°C ~ 125°C 封装/外壳:32-WFQFN 裸露焊盘 包装:Digi-Reel® 产品目录页面:1303 (CN2011-ZH PDF) 其它名称:LM3754SQDKR |
| LT3757EMSE#PBF | 制造商:Linear Technology 功能描述:DC-DC CONTROLLER SEPIC 1MHZ 制造商:Linear Technology 功能描述:DC-DC CONTROLLER, SEPIC, 1MHZ, MSOP-10 |
| LT3757EMSE#TRPBF | 功能描述:IC REG CTRLR PWM CM 10-MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR) |
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