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IRS2548D LED Driver IC PFC and Half Bridge driver combo Peter Green – LED Group Mgr. Energy Saving Products Business Unit April 2011. 1. LED Lighting Introduction. Small LEDs developed in 1960s for indication High Brightness / High Power LEDs now available
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IRS2548DLED Driver ICPFC and Half Bridge driver comboPeter Green – LED Group Mgr Energy Saving Products Business Unit April 2011 1
LED Lighting Introduction • Small LEDs developed in 1960s for indication • High Brightness / High Power LEDs now available • Lumens per Watt better than Incandescent / Halogen lamps • Lumens per Watt equal or better than Fluorescent or HID lamps • HB/HP LEDs being adopted in general illumination • Typical applications; bulb replacements, light fixtures, • Street lamps • LEDs have longer operating life, typically 50000 hours • LEDs offer better reliability / durability • LEDs are easier to control and dim • LEDs offer reduced Lumen depreciation • (less light output reduction over time) • LEDs are normally DC driven • LEDs are driven by constant current
High Power LED Applications • LED Street Light • Typically 120W per cobra head • Example opposite uses 4 x 30W • LED panels • One LED driver per cobra head • Typically 1.4A output • Single or multi channel output • Optimize for efficiency (series LED • connection) or redundancy (4 channel • output) • High Lumen output / directed light • Controllable light output (PWM or linear dimming) • Galvanically isolated low voltage outputs (safety) • Open and short circuit protected • Wide input voltage range 90 to 305VAC • High power factor and low THD
Power Factor Control is Power Quality • “Power Factor” • Relationship between voltage and current waveforms • Measure of “power quality” that affects transmission network efficiency • PFC regulations apply to: • China : China Compulsory Certificate (CCC) • Europe : IEC 1000-3-2 • Japan : JIC C 61000-3-2 • For products >75W (>26W for lighting applications)
IRS2548D • Critical conduction mode (CrCM) PFC Control • THD reduction by on time modulation • Variable frequency oscillator (current controlled) • Half bridge driver • PWM dimming input (ENN) also disables PFC • Over current protection (PFC and Half bridge) • Fixed internal 1.6uS half bridge (HO and LO) dead time • Internal bootstrap MOSFET • Internal 15.6V zener clamp diode on VCC • Micropower startup (250uA) • Latch immunity and ESD protection • Maximum half bridge offset voltage 600V • Gate drive output current (PFC, HO, LO) +/-0.5A • 14 lead SOIC package • For LED driver and SMPS applications (typically > 50W) • For wide AC input voltage range 90 to 305 VAC
IRS2548D Target Applications Handheld LED Lamps OFF LINE LED LIGHT FIXTURES AUTOMOTIVE LCD Back Light Fluorescent Replacement Incandescent Replacement HID Replacement Handheld Devices
Two Stage LED Driver IRS2548D PFC + Half Bridge Driver IC Combo IC Solution 7
IRS2548D Typical Schematic Bus Voltage Feedback Frequency Control Input Half Bridge MOSFETs Voltage and Current Feedback PFC MOSFET OPTO ISOLATOR (Feedback) Rectifier Diodes/MOSFETs
IRS2548D Demo Board IRPLLED5 Features: High output current regulation 90-305VAC universal input Dimmable with 1-10V DC input Non-latched shutdown against output over-voltage Using IRS2548DS LED control IC
Test Results Load: 2 x Eco Lumens EPAD connected in series Driving 32 x Samsung Sunnix6 HPLED packs Total Power = 55W
Output V-I Characteristic Green = LED Voltage Blue = LED Current Open circuit voltage < 60V Current ripple ~15% Short circuit current = 1.5A
Multi Channel LED Concept IRS2548D Based Power Stage • One main power converter supplies 48V isolated DC bus • Wide input voltage range 90 to 305VAC • High power factor and low THD • Output modules provide 2 x 700mA regulated current outputs
IRS2548D IC Summary • For LED driver and SMPS applications (typically > 50W) • For wide AC input voltage range 90 to 305 VAC • High Power Factor and Low THD • Resonant Half Bridge Topology / Soft Switching • Efficiency better than 85% above 50W • Efficiency improves at higher power levels • Suitable for isolated LED drivers > 50W • Efficiency and flexibility surpasses Flyback solution above 50W • Protected against short circuit in primary and secondary stages • Enables regulated output current loop for LED driving • Incorporates PWM dimming input, allows dimming to ~2% output