Prema PR4404 LED升压驱动方案
Prema公司的PR4404是适用于0.5W/1W大功率LED的低压升压驱动器，能从单电池(1.2V/1.5V)提供高达150mA LED电流或从两节电池(2.4V/3.0V)提供高达300mA LED电流.因此，PR4404可广泛用在LED火炬，LCD屏背光，家庭照明和玩具.本文介绍了PR4404主要特性， 方框图， 典型应用电路， 测试电路， 手电筒应用电路， LED串驱动电路图以及PWM控制的LED驱动电路图.
Low Voltage Boost Driver PR4404 for 0.5W / 1W Power LEDs
The PR4404 is a step-up converter for white LEDs， operating with single battery cell
supply (1.2/1.5V) at up to 150mA LED current or dual cell supply (2.4/3.0V) at up to
300mA LED current.
A minimum part count allows compact and cost-efficient solutions.
The converter can be switched on and off with a logic signal， which is useful e.g. for PWM
control， timer circuits etc.
PR4404主要特性:
minimum startup voltage 1.0V
supply by one or two battery cells
low number of external components
battery deep discharge protection
应用:
LED torches
LCD panel backlighting
home lighting
toys
图1. PR4404方框图
图2.PR4404典型应用电路
图3.PR4404测试电路
图4.手电筒应用电路
150mA LED电流所用元件:
Vcc: 1.2...1.5V (nominal)
C1a: 1μF
C1b: 100μF/6.3V
L1: 1.0μH， Isat 1.2A
D1: MBRS140 or 1N5817
Rs: 1.3 
C2a: 470nF
C2b: 22μF/6.3V
300mA LED电流所用元件:
Vcc: 2.4...3.0V (nominal)
C1a: 470nF
C1b: 100μF/6.3V
L1: 1.5μH， Isat 1.6A
D1: MBRS140 or 1N5817
Rs: 0.67 
C2a: 470nF
C2b: 22μF/6.3V
图5.PR4404驱动LED串电路图
图6.PR4404驱动PWM控制LED电路图
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