LED5000PHR STMicroelectronics

LED5000 3 A monolithic step-down current source with dimming capability Datasheet - production data Applications High brightness LED driving Street lighting Signage Halogen bulb replacement General lighting Description The LED5000 device is an 850 kHz fixed switching frequency monolithic step-down DC-DC Features converter designed to operate as a precise 5.5 V to 48 V operating input voltage range constant current source with an adjustable 850 kHz fixed switching frequency current capability up to 3 A DC. The embedded 200 mV typ. current sense voltage drop PWM dimming circuitry features LED brightness Buck / buck-boost / floating boost topologies control. The regulated output current level is set PWM dimming by connecting a sensing resistor to the feedback 3% output current accuracy pin. The 200 mV typical RSENSE voltage drop overtemperature enhances performance in terms of efficiency. The 200 m typical RDSON size of the overall application is minimized thanks Peak current mode architecture to the high switching frequency and its Short-circuit protection compatibility with ceramic output capacitors. The device is fully protected against overheating, Compliant with ceramic output capacitors overcurrent and output short-circuit. The Inhibit for zero current consumption LED5000 is available in an HSOP8 package. Thermal shutdown Figure 1: Typical application circuit July 2017 DocID023951 Rev 6 1/56 www.st.com This is information on a product in full production. Contents LED5000 Contents 1 Pin settings ...................................................................................... 4 1.1 Pin connection ................................................................................... 4 1.2 Pin description ................................................................................... 4 2 Maximum ratings ............................................................................. 5 2.1 Maximum ratings ............................................................................... 5 2.2 Thermal data ..................................................................................... 5 2.3 ESD protection .................................................................................. 5 3 Electrical characteristics ................................................................ 6 4 Functional description .................................................................... 8 4.1 Power supply and voltage reference ................................................. 8 4.2 Voltage monitor ................................................................................. 9 4.3 Soft-start ........................................................................................... 9 4.4 Dimming block ................................................................................. 10 4.5 Inhibit block ..................................................................................... 10 4.6 Error amplifier .................................................................................. 10 4.7 Thermal shutdown ........................................................................... 10 5 Application notes - buck conversion ........................................... 11 5.1 Closing the loop .............................................................................. 11 5.2 G (s) control to output transfer function ........................................ 11 CO 5.3 Error amplifier compensation network ............................................. 13 5.4 LED small signal model ................................................................... 14 5.5 Total loop gain ................................................................................. 16 5.6 Compensation network design ........................................................ 16 5.7 Example of system design .............................................................. 17 5.8 Dimming operation .......................................................................... 19 5.8.1 Dimming frequency vs. dimming depth ............................................ 21 5.9 Component selection ...................................................................... 23 5.9.1 Sensing resistor ................................................................................ 23 5.9.2 Inductor and output capacitor selection ............................................ 23 5.9.3 Input capacitor .................................................................................. 25 5.10 Layout considerations ..................................................................... 27 5.11 Thermal considerations ................................................................... 28 5.12 Short-circuit protection .................................................................... 30 2/56 DocID023951 Rev 6