CXLE8856 DC转换器可调节的输出电流内部智能模块自动调节连接在反馈引脚FB和接地之间的外部电流感测电阻器Rs进行编程驱动双电池碱性电池的高达1A的负载

CXLE8856是一个设置的DC-DC转换器，提供可调节的输出电流。设备以1.0兆赫的恒定频率切换，允许使用小值外部电感和陶瓷电容器。CXLE8856用于驱动双电池碱性电池的高达1A的负载。LED电流可由内部智能模块自动调节，并由连接在反馈引脚（FB）和接地之间的外部电流感测电阻器Rs进行编程。低95mV（典型值）反馈电压降低功率为提高效率而损失卢比。该装置内置2A、100mΩNMOS开关，即使在重载情况下也能提供高效率。在停机期间模式下，反馈电阻器Rs和负载完全断开，电流消耗降低到1uA
LED功率效率：高达90%
电流精度：5%
低启动电压：0.9V
低保持电压：0.75V
1MHz开关频率
使用小型、低调的外部组件

目录

1.产品概述                       2.产品特点
3.应用范围                       4.下载产品资料PDF文档 
5.产品封装图                     6.电路原理图                   
7.功能概述                        8.相关产品

一,产品概述(General Description)    

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   The CXLE8856 is a set-up DC-DC converter that delivers a regulated output current. The device switches at a 1.0MHz constant frequency, allowing for the
use of small value external inductor and ceramic capacitors.The CXLE8856 is targeted to be used for driving loads up to 1A from a two-cell alkaline battery.
    The LED current can be auto adjusted by internal smart module and programmed by the external current sense resistor, Rs,connected between the feedback pin (FB) and ground. A low 95mV(TYP.) feedback voltage reduces the power
loss in the Rs for better efficiency. With its internal 2A,100mΩ NMOS switch, the device can provide high efficiency even at heavy load. During the shutdown
mode, the feedback resistor Rs and the load are completely disconnected and the current consumption is reduced to 1uA.The CXLE8856 is available in the 6-lead
SOT-23-6L package.
二.产品特点(Features)

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LED Power Efficiency: up to 90%
Current Accuracy: 5%(Vin =3.6V to 1.8V
@Vf =3.7V)
Low Start-Up Voltage: 0.9V
Low Hold Voltage:0.75V
1MHz Switching Frequency
Uses small, Low Profile External Components
Low RDS(ON) : 100mΩ (TYP.)
Over Temperature Protection
Low Profile SOT-23-6L Package
三,应用范围 (Applications)

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White LED Torch (Flashlight)
White LED Camera Flash
DSC(Digital Still Camera)Flash
Cellular Camera Phone Flash
PDA Camera Flash
Camcorder Torch(Flashlight) Lamp
四.下载产品资料PDF文档 

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需要详细的PDF规格书请扫一扫微信联系我们，还可以获得免费样品以及技术支持！

 

五,产品封装图 (Package)

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Pin No.	Pin Name	Pin Function
1	SW	Switching Pin.
2	GND	Ground Pin.
3	FB	Feedback Pin.
4	EN	Chip Enable(Active High).
5	VOUT	Output Voltage Pin.
6	VIN	Input Supply.

六.电路原理图

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七,功能概述

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Inductor Selection
The CXLE8856 can use small value inductors due to its switching frequency of 1MHz. The value of inductor will focus in the range of 2.2uH to 4.7uH for most CXLE8856 applications. In typical high current white LED applications,it is recommended to use a 4.7uH inductor. The inductor should have low DCR (DC resistance) to minimize the IR power loss, and it requires a current rating of 2A to handle the peak inductor current without saturating. 
Capacitor Selection
An input capacitor is required to reduce the input ripple and noise for proper operation of the CXLE8856. For good input decoupling,  Low  ESR(equivalent  series  resistance) capacitors should be used at the input. At least 2.2uF input capacitor  is  recommended  for  most  applications. A minimum output capacitor value of 6.8uF is recommended under normal operating conditions, while a 10uF-22uF capacitor may be required for higher power LED current. A reasonable value of the output capacitor depends on the LED current. The ESR of the output capacitor is the important parameter to determine the output voltage ripple of the converter, so low ESR capacitors should be used at the output to reduce the output voltage ripple. The small size of ceramic capacitors is an excellent choice for CXLE8856 applications. The X5R and X7R types are preferred because they maintain capacitance over wide voltage and temperature ranges.
Diode Selection
It's indispensable to use a Schottky diode rated at 2A with the CXLE8856. Using a Schottky diode with a lower forward voltage drop is better to improve the power LED efficiency, and its voltage rating should be greater than the output voltage. In application, the ON Semiconductor MBRA210LT3G is recommended. 
LED Current Setting
The LED current is set by the single external Rs resistor connected to the FB pin as shown in the typical application circuit on page 1. The typical FB reference is internally regulated to 95mV(TYP.). The LED current is 95mV/Rs. It's recommended to use a 1% or better precision resistor for the better LED current accuracy.
The formula and table 1 for Rs selection are shown as follows:
Rs=95mV/ILED
PCB Layout Guidelines
For best performance of the CXLE8856, the following guidelines must be strictly followed. Input and Output capacitors should be placed close to the IC and connected to ground plane to reduce noise coupling.Keep the main current traces as possible as short and wide.SW node of DC-DC converter is with high frequency voltage swing. It should be kept at a small area.Place the feedback components as close as possible to the IC and keep away from the noisy devices.
八,相关产品                  更多同类产品.......

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升压型LED射灯驱动IC
型号	工作电压范围	输出电流	输出电流精度	效率	工作频率	调光功能	封装
CXLE8856	0.9V-6.0V	1A	-	90%	1.0 MHz	PWM调光	SOT-26
CXLE8857B	0.8V-5.5V	外置MOS/15W	3%	90%	700KHz	PWM调光500Hz-1KHz	SOT-26
CXLE8858	3V-24V	内置2A MOS	2%	90%	1.2MHz	PWM调光	SOT-26
CXLE8858B	2.7V-6.5V	内置2.8A MOS	2%	90%	1MHz	PWM调光	SOT-26
CXLE8859	2.5V-30V	内置3A MOS	2%	90%	460KHz	模拟调光/PWM调光	SOP-8
CXLE8860	2.2V-6V	内置3A MOS	2%	90%	800KHz	PWM调光	SOP-8
CXLE8861	2.2V-6V	内置3A MOS	2%	90%	800KHz	PWM调光	DFN3*3-8
CXLE8862	10V-35V	内置3A MOS	2%	90%	800KHz	PWM调光	SOP-8
CXLE8863	4.5V--24V	1A	2%	90%	800KHz	PWM调光	ESOP8
CXLE8864	3.6V-26V	2A	2%	92%	400KHz	PWM调光	SOP-8
CXLE8865	3.6V-26V	2A	2%	92%	400KHz	PWM调光	SOP-8
CXLE8865B	5V-45V	2A	2%	93%	400KHz	PWM调光	SOP-8
CXLE8866	8V-32V	内置8A MOS	2%	92%	1MHz	PWM调光	SOP-14
CXLE8867	8V-32V	外置MOS/36W	2%	94%	1MHz	PWM调光	ESOP-8
CXLE8868	3.6V-36V	4A	2%	94%	180KHz	PWM调光	TO252-5L
CXLE8869	5.0V-36V	5A	2%	94%	180KHz	PWM调光	TO-263-5L