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参数资料
| 型号： | LT3511HMS#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 0.43 A SWITCHING REGULATOR, 650 kHz SWITCHING FREQ-MAX, PDSO12 |
| 封装： | LEAD FREE, PLASTIC, MSOP-12/16 |
| 文件页数： | 4/26页 |
| 文件大小： | 298K |
| 代理商： | LT3511HMS#TRPBF |
LT3511
12
3511fb
Leakage Inductance and Clamp Circuits
Transformer leakage inductance (on either the primary or
secondary) causes a voltage spike to appear at the primary
after the output switch turns off. This spike is increasingly
prominent at higher load currents where more stored en-
ergy must be dissipated. When designing an application,
adequate margin should be kept for the effect of leakage
voltage spikes. In most cases the reflected output voltage
on the primary plus VIN should be kept below 100V. This
leaves at least 50V of margin for the leakage spike across
line and load conditions. A larger voltage margin will be
needed for poorly wound transformers or for excessive
leakageinductance.Figure5illustratesthispoint.Minimize
transformer leakage inductance.
A clamp circuit is recommended for most applications.
Two circuits that can protect the internal power switch
include the RCD (resistor-capacitor-diode) clamp and the
DZ (diode-Zener) clamp. The clamp circuits dissipate the
stored energy in the leakage inductance. The DZ clamp
is the recommended clamp for the LT3511. Simplicity of
design,highclampvoltages,andlowpowerlevelsmakethe
DZ clamp the preferred solution. Additionally, a DZ clamp
ensures well defined and consistent clamping voltages.
Figure 5 shows the clamp effect on the switch waveform
and Figure 6 shows the connection of the DZ clamp.
<100V
<140V
<150V
VSW
tOFF > 400ns
with Clamp
TIME
tSP < 150ns
3511 F05
<100V
<150V
VSW
VLEAKAGE
tOFF > 400ns
without Clamp
TIME
tSP < 150ns
Figure 5. Maximum Voltages for SW Pin Flyback Waveform
3511 F06
LS
D
Z
Figure 6. DZ Clamp
Proper care must be taken when choosing both the diode
and the Zener diode. Schottky diodes are typically the best
choice, but some PN diodes can be used if they turn on
fast enough to limit the leakage inductance spike. Choose
a diode that has a reverse-voltage rating higher than the
maximum switch voltage. The Zener diode breakdown
voltageshouldbechosentobalancepowerlossandswitch
voltage protection. The best compromise is to choose the
largest voltage breakdown. Use the following equation to
make the proper choice:
VZENER(MAX) ≤ 150V – VIN(MAX)
For an application with a maximum input voltage of 72V,
choose a 68V VZENER which has VZENER(MAX) at 72V, which
will be below the 78V maximum.
The power loss in the clamp will determine the power rat-
ing of the Zener diode. Power loss in the clamp is highest
applicaTions inForMaTion
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3511IMS#PBF | 功能描述:IC REG FLYBK ISO ADJ .24A 16MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LT3511IMS#TRPBF | 功能描述:IC REG FLYBK ISO ADJ .24A 16MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LT3511MPMS#PBF | 功能描述:IC REG FLYBK ISO ADJ .24A 16MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LT3511MPMS#TRPBF | 功能描述:IC REG FLYBK ISO ADJ .24A 16MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LT3512 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Monolithic High Voltage Isolated Flyback Converter |
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