FAN5331SX【PDF 6/10 页】IC LED DRVR WHITE BCKLGT SOT23-5

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Sheet目录325

2页 3页 4页 5页 [6页]7页 8页 9页 10页

Block Diagram

SHDN

Shutdown

V IN

Circuitry

+ Over

Voltage

- Comp

1.15 x V REF

Thermal

Shutdown

FB 3

Error

Amp

Comp

Driver

Ramp

Generator

Oscillator

Reference

Current Limit

Comparator

Soft-Start

Amp

0.05

GND

Figure 4. Block Diagram

V OUT = V REF ? 1 + ------ 1 - ?

Circuit Description

The FAN5331 is a pulse-width modulated (PWM) current-mode

boost converter. The FAN5331 improves the performance of bat-

tery powered equipment by signi?cantly minimizing the spectral

distribution of noise at the input caused by the switching action of

the regulator. In order to facilitate effective noise ?ltering, the

switching frequency was chosen to be high, 1.6MHz. An internal

soft start circuitry minimizes in-rush currents. The timing of the soft

start circuit was chosen to reach 95% of the nominal output voltage

within maximum 5mS following an enable command when V IN =

2.7V, V OUT = 15V, I LOAD = 35mA and C OUT (EFFECTIVE) = 3.2 μ F.

The device architecture is that of a current mode controller with

an internal sense resistor connected in series with the N-chan-

nel switch. The voltage at the feedback pin tracks the output

voltage at the cathode of the external Schottky diode (shown in

the test circuit). The error ampli?er ampli?es the difference

between the feedback voltage and the internal bandgap refer-

ence. The ampli?ed error voltage serves as a reference voltage

to the PWM comparator. The inverting input of the PWM com-

parator consists of the sum of two components: the ampli?ed

control signal received from the 50m ? current sense resistor

and the ramp generator voltage derived from the oscillator. The

oscillator sets the latch, and the latch turns on the FET switch.

Under normal operating conditions, the PWM comparator resets

the latch and turns off the FET, thus terminating the pulse.

Since the comparator input contains information about the out-

put voltage and the control loop is arranged to form a negative

feedback loop, the value of the peak inductor current will be

adjusted to maintain regulation.

Every time the latch is reset, the FET is turned off and the cur-

rent ?ow through the switch is terminated. The latch can be

FAN5331 Rev. 1.0.1

reset by other events as well. Over-current condition is moni-

tored by the current limit comparator which resets the latch and

turns off the switch instantaneously within each clock cycle.

Over-Voltage Protection

The voltage on the feedback pin is sensed by an OVP Compar-

ator. When the feedback voltage is 15% higher than the nominal

voltage, the OVP Comparator stops switching of the power tran-

sistor, thus preventing the output voltage from going higher.

Applications Information

Setting the Output Voltage

The internal reference is 1.23V (Typical). The output voltage is

divided by a resistor divider, R1 and R2 to the FB pin. The out-

put voltage is given by

? R 2 ?

According to this equation, and assuming desired output volt-

age of 15V, good choices for the feedback resistors are,

R 1 =150k ? and R 2 =13.4k ? .

Inductor Selection

The inductor parameters directly related to device performances

are saturation current and dc resistance. The FAN5331 oper-

ates with a typical inductor value of 10μH. The lower the dc

resistance, the higher the ef?ciency. Usually a trade-off between

inductor size, cost and overall ef?ciency is needed to make the

optimum choice.

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FAN5331SX_Q 功能描述:IC LED DRVR WHITE BCKLGT SOT23-5 RoHS:是类别:集成电路 (IC) >> PMIC - LED 驱动器系列:- 标准包装:1 系列:- 恒定电流:- 恒定电压:- 拓扑:PWM，切换式电容器（充电泵）输出数:1 内部驱动器:是类型 - 主要:背光类型 - 次要:白色 LED 频率:642kHz 电源电压:2.7 V ~ 5.5 V 输出电压:5V 安装类型:表面贴装封装/外壳:10-VFDFN 裸露焊盘供应商设备封装:10-VSON 包装:剪切带 (CT) 工作温度:-30°C ~ 85°C 产品目录页面:1371 (CN2011-ZH PDF) 其它名称:BD1603NUV-E2CT

FAN5332_BBC3086B WAF 制造商:Fairchild Semiconductor Corporation 功能描述:

FAN5332A 制造商:FAIRCHILD 制造商全称:Fairchild Semiconductor 功能描述:High Efficiency, High Current Serial LED Driver and OLED Supply with 30V Integrated Switch

FAN5332ASX 功能描述:直流/直流开关转换器 1.6MHz BOOST REGULATOR RoHS:否制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT

FAN5332ASX_NL 功能描述:LED照明驱动器 1.6MHz Boost regulator RoHS:否制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N

FAN5333A 制造商:FAIRCHILD 制造商全称:Fairchild Semiconductor 功能描述:High Efficiency, High Current Serial LED Driver with 30V Integrated Switch

FAN5333ASX 功能描述:直流/直流开关转换器 SYSTEM_POWER RoHS:否制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT

FAN5333B 制造商:FAIRCHILD 制造商全称:Fairchild Semiconductor 功能描述:High Efficiency, High Current Serial LED Driver with 30V Integrated Switch

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