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参数资料
| 型号： | LT3751IFE#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 电源管理 |
| 英文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO20 |
| 封装： | 4.40 MM, LEAD FREE, PLASTIC, TSSOP-20 |
| 文件页数： | 14/34页 |
| 文件大小： | 403K |
| 代理商： | LT3751IFE#TRPBF |
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LT3751
21
3751fb
Figure 11. Effects of RC Snubber
Figure 10. RC Snubber Circuit
APPLICATIONS INFORMATION
Two problems can arise from large VD,LEAK. First, the
magnitude of the spike may require an NMOS with an
unnecessarily high V(BR)DSS which equates to a larger
RDS(ON). Secondly, the VDRAIN node will ring—possibly
below ground—causing false tripping of the DCM
comparator or damage to the NMOS switch (see Figure
11). Both issues can be remedied using a snubber. If
leakage inductance causes issues, it is recommended to
use a RC snubber in parallel with the primary winding, as
shown in Figure 10. Size CSNUB and RSNUB based on the
desired leakage spike voltage, known leakage inductance,
and an RC time constant less than 1μs. Otherwise, the
leakage voltage spike can cause false tripping of the VOUT
comparator and stop charging prematurely.
Figure 11 shows the effect of the RC snubber resulting in
a lower voltage spike and faster settling time.
3751 F11
LPRI
RSNUB
CSNUB
LLEAK
CVDRAIN
0V
3751 F12
VDRAIN
(WITH
SNUBBER)
VDRAIN
(WITHOUT
SNUBBER)
IPRI
NMOS DIODE
CONDUCTS
LOW NOISE REGULATION
The LT3751 has the option to provide a low noise regulated
output voltage when using a resistive voltage divider
from the output node to the FB pin. Refer to the Selecting
Component Parameters section to design the transformer,
NMOS power switch, output diode, and sense resistor.
Use the following equations to select the feedback resistor
values based on the power dissipation and desired output
voltage:
R
FBH =
V
OUT 1.22
()2
P
D
; Top Feedback Resistor
R
FBL =
1.22
V
OUT 1.22
R
FBH ; Bottom Feedback Resistor
RFBH, depending on output voltage and type used, may
require several smaller values placed in series. This will
reduce the risk of arcing and damage to the feedback
resistors. Consult the manufacturer’s rated voltage
specication for safe operation of the feedback resistors.
The LT3751 has a minimum periodic refresh frequency
limit of 23kHz. This drastically reduces switching frequency
components in the audio spectrum. The LT3751 can
operate with no-load, but the regulation scheme switches
to no-load operation and audible noise and output voltage
ripple increase. This can be avoided by operating with a
minimum load current.
Minimum Load Current
Periodic refresh circuitry requires an average minimum
load current to avoid entering no-load operation. Usually,
the feedback resistors should be adequate to provide this
minimum load current.
I
LOAD(MIN) ≥
L
PRI I
2
PK 23kHz
100 V
OUT
IPK is the peak primary current at maximum power delivery.
The LT3751 will enter no-load operation if the minimum
load current is not met. No-load operation will prevent the
application from entering a runaway condition; however,
the output voltage will increase 10% over the nominal
regulated voltage.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3751IUFD | 制造商:LINER 制造商全称:Linear Technology 功能描述:Capacitor Charger Controller with Regulation |
| LT3751IUFD#PBF | 功能描述:IC CTRLR CAP CHRGR 4.75V 20-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 电源管理 - 专用 系列:- 标准包装:1 系列:- 应用:手持/移动设备 电流 - 电源:- 电源电压:3 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:14-WFDFN 裸露焊盘 供应商设备封装:14-LLP-EP（4x4） 包装:Digi-Reel® 配用:LP3905SD-30EV-ND - BOARD EVALUATION LP3905SD-30 其它名称:LP3905SD-30DKR |
| LT3751IUFD#TRPBF | 功能描述:IC CTRLR CAP CHRGR 4.75V 20-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 电源管理 - 专用 系列:- 标准包装:1 系列:- 应用:手持/移动设备 电流 - 电源:- 电源电压:3 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:14-WFDFN 裸露焊盘 供应商设备封装:14-LLP-EP（4x4） 包装:Digi-Reel® 配用:LP3905SD-30EV-ND - BOARD EVALUATION LP3905SD-30 其它名称:LP3905SD-30DKR |
| LT3751IUFD-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Capacitor Charger Controller with Regulation |
| LT3751IUFD-TR | 制造商:LINER 制造商全称:Linear Technology 功能描述:Capacitor Charger Controller with Regulation |
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