ST公司的LED5000是850kHz固定開關頻率單片降壓DC/DC轉換控制器,驅動電流可高達3A,PWM LED亮度調光,輸入電壓5.5V-48V,± 3%輸出電流精度,主要用于高亮度LED驅動,街燈照明,信號標志牌和通用照明.本文介紹了LED5000主要特性,功能框圖,幾種典型應用電路,以及3A降壓LED驅動器STEVAL-ILL056V1主要特性和電路圖.

The LED5000 device is an 850 kHz fixedswitching frequency monolithic step-down DC-DC converter designed to operate as a preciseconstant current source with an adjustable current capability up to 3 A DC. The embedded PWMdimming circuitry features LED brightness control. The regulated output current level is set byconnecting a sensing resistor to the feedback pin.

The 200 mV typical RSENSE voltage dropenhances perance in terms of efficiency. Thesize of the overall application is minimized thanksto the high switching frequency and itscompatibility with ceramic output capacitors. Thedevice is fully protected against overheating,overcurrent and output short-circuit. TheLED5000 is available in an HSOP8 package.

LED5000主要特性:
? 5.5 V to 48 V operating input voltage range
? 850 kHz fixed switching frequency
? 200 mV typ. current sense voltage drop
? Buck / buck-boost / floating boost topologies
? PWM dimming
? ± 3% output current accuracy overtemperature
? 200 m ohmtypical RDSON
? Peak current mode architecture
? Short-circuit protection
? Compliant with ceramic output capacitors
? Inhibit for zero current consumption
? Thermal shutdown
LED5000應用:
? High brightness LED driving
? Street lighting
? Signage
? Halogen bulb replacement
? General lighting

圖1.LED5000功能框圖

圖2.LED5000典型應用電路圖

圖3.LED5000評估板應用電路圖

3A降壓LED驅動器STEVAL-ILL056V1

The STEVAL-ILL056V1 is a product evaluation board based on the LED5000, an 850 kHz fixed switching frequency monolithic step-down DC-DC converter designed to operate as a precise constant current source with an adjustable current capability up to 3 A DC. The embedded PWM dimming circuitry features LED brightness control. The regulated output current level is set by connecting a sensing resistor to the feedback pin. The 200 mV typical RSENSE voltage drop enhances perance in terms of efficiency. The size of the overall application is minimized thanks to the high switching frequency and its compatibility with ceramic output capacitors. The device is fully protected against overheating, overcurrent and output short-circuit.

3A降壓LED驅動器STEVAL-ILL056V1主要特性:

5.5 V to 48 V operating input voltage range
850 kHz fixed switching frequency
200 mV typ. current sense voltage drop
Buck / buck-boost / floating boost topologies
PWM dimming
±3% output current accuracy over temperature
200 mOhm typical R_DS(on)
Peak current mode architecture
Short-circuit protection
Compliant with ceramic output capacitors
Inhibit for zero current consumption
Thermal shutdown
RoHS compliant

圖6.3A降壓LED驅動器STEVAL-ILL056V1外形圖

圖7.3A降壓LED驅動器STEVAL-ILL056V1電路圖