收藏本站
SC4538
Applications Information (continued)
must endure high voltage for an extended period of
time.
D
1
V IN
V OUT
Soft-Start
The soft-start mode reduces in-rush current by utilizing
the external compensation network. As the error amplifier
I IN
V OUT I OUT
V IN
slowly charges the COMP node voltage, the duty cycle of
the boost switch ramps from 0% to its final value once in
regulation. The gradual increase of the duty cycle slowly
charges the output capacitor and limits in-rush current
during start up. Soft-start is implemented only when the
input power is cycled.
D is the duty cycle for continuous operation. Effi ciency (η)
can be approximated by using the curves provided in the
Typical Characteristics section. Table 1 lists inductors that
have been proven to work with SC4538.
Table 1 -- Recommended Inductors
Thermal Shutdown
A thermal shutdown system is included for protection in
the event the junction temperature exceeds 155°C. In
thermal shutdown, the on-chip power switch is disabled.
Switching and sinking resumes when the temperature
drops by 20°C.
Current Limit
Part Number
Coilcraft
LPS4018-223ML
Murata
LQH43CN150K03
Murata
LQH32CN150K53
Value
(μH)
22
15
15
DCR
(Ω)
0.360
0.320
0.580
Rated
Current (A)
0.70
0.570
0.300
Toler-
ance
±20%
±10%
±10%
Dimensions
(L x W x H)
(mm)
3.9 x 3.9 x 1.7
4.5 x 3.2 x 2.6
3.2 x 2.5 x 1.55
The power switch of the boost converter is protected by
an internal current limit function. The switch is opened
when the current exceeds the maximum switch current
value.
Inductor Selection
The inductor value should be within the range of 4.7μH to
22μH. The DCR needs to be considered when selecting
the inductor to ensure optimum effi ciency. The largest
inductor package that can be tolerated in the circuit area
Capacitor Selection
The input capacitor should be at least 2.2μF. A larger
capacitor will reduce the voltage ripple on the input. The
output capacitor values can range from 0.22μF to 1μF. The
compensation capacitor value should be 47nF. Capacitors
of X5R type material or better can be used for any of the
capacitors. See Table 2 for the recommended capacitors.
Table 2 -- Recommended Capacitors
should be used since the DCR generally decreases with
increasing package size.
Part Number
Value
(μF)
Rated
Voltage (V)
Type
Case Size
Input Capacitor
The saturation current of the inductor should be much
higher than the peak current of the internal boost switch
Murata
GRM188C70J225KE20
2.2
6.3
X7S
0603
to ensure that the inductor never enters saturation during
normal operation of the part. The equation to calculate
Output Capacitor
the peak inductor current is:
Murata
GRM21BR71H105KA12L
1.0
50
X7R
0805
I L(Peak)
I IN
I L
2
Compensation Capacitor
Taiyo Yuden
EMK105BJ473KV-F
0.047
16
X7R
0402
where
I L
V IN D
L f osc
11
发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

*型号 *数量 厂商 批号 封装
添加更多采购

我的联系方式

*
*
*
相关PDF资料
SC4539ULTRT IC LED DRIVR CONST CURRENT 8MLPD
SC4540ULTRT IC LED DRIVR CONST CURRENT 8MLPD
SC4541SKTRT IC LED DRVR BACKLIGHT SOT23-6
SC5010ULTRT IC LED DRVR BACKLIGHT I2C 28QFN
SC600BIMLTRT IC LED DRIVR WHITE BCKLGT 10-MLP
SC618ULTRT IC LED DRIVER PHOTO FLASH 10-MLP
SC620ULTRT IC LED DRIVER LINEAR 16-MLPQ
SC628AULTRT IC LED DRIVER
相关代理商/技术参数
SC4539 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:High Effi ciency Boost Converter for up to 6 LEDS
SC4539_08 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:High Effi ciency Boost Converter for up to 6 LEDS
SC4539EVB 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:High Effi ciency Boost Converter for up to 6 LEDS
SC4539ULTRT 功能描述:IC LED DRIVR CONST CURRENT 8MLPD RoHS:是 类别:集成电路 (IC) >> PMIC - LED 驱动器 系列:- 标准包装:60 系列:- 恒定电流:- 恒定电压:- 拓扑:线性（LDO），PWM，升压（升压） 输出数:8 内部驱动器:是 类型 - 主要:背光 类型 - 次要:RGB，白色 LED 频率:500kHz ~ 1.5MHz 电源电压:4.75 V ~ 26 V 输出电压:45V 安装类型:* 封装/外壳:* 供应商设备封装:* 包装:* 工作温度:-40°C ~ 85°C
SC453EVB 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:Portable, VID Programmed Single Phase Power Supply Controller
SC453MLTRT 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:Portable, VID Programmed Single Phase Power Supply Controller
SC453TS.TRT 制造商:SEMTECH 功能描述:I.C.
SC453TSTRT 制造商:Semtech Corporation 功能描述:Power Supply Controller 28-Pin TSSOP T/R