EVALHVLED805 STMicroelectronics

EVALHVLED805 4.2 W off-line LED driver with primary side regulation Data brief Features Input voltage range (V ): 185 - 265 V IN AC Main frequency (f ): 50 - 60 Hz L Maximum (rated) output power: 4.2 W Output: I = 350 mA 5% OUT Over voltage = 12 V max Current ripple < 10% I OUT Minimum switching frequency in normal mode: 70 kHz Target average efficiency (from 1 to 3 LEDs) > 70 % Maximum input power in no-load < 100 mW Description The EVALHVLED805 is a demonstration board equipped with the new HVLED805 PWM current mode LED driver and is designed for European mains. It can control, with very good accuracy, from 1 to 3 LEDs having a nominal current of 350 mA. The HVLED805 has integrated high voltage startup and an 800 V power MOSFET. The high MOSFET s breakdown voltage allows very robust and reliable applications and reduces the size of the snubber and the relative power dissipation. Its accurate primary-current control eliminates the need of the optocoupler which impacts the cost, the compactness and the lifetime of the application while still maintaining a very good LED accuracy (below 5 %). Moreover, this converter, specifically designed for quasi- resonant (QR) flyback converters, enables very low turn-on losses and EMI emissions. November 2011 Doc ID 18457 Rev 2 1/9 For further information contact your local STMicroelectronics sales office. www.st.com 9 , 5 , 5 , 5 , 5 *1 Electrical schematic EVALHVLED805 1 Electrical schematic Figure 1. EVALHVLED805 electrical schematic / X ) O EDFN DVU 7 I R 36 + 67 - 9 P - & 5 DF 9 5 % 6 5 0 & Q) N & & 5 X X N & & X X + / 677 & Q 5 // & X 5 N 8 & 1 1 1 1 0* /( , (6285& 6285&( + 9/( 5 N & Q & & 5 5 Q 5 Q N 1.1 Efficiency measurement Figure 2. Efficiency measurement with one, two or three LEDs QF D 9 F D 9 F D 9 F 9 >9 728 - V The efficiency is always higher than 70 % when two or three LEDs are connected, whereas it drops with one LED. The reason is that at low output voltage, the auxiliary voltage is not able to supply the IC and the internal HV current generator self supplies the Vcc pin, thus dissipating a power proportional to VIN. The output current has been measured with two or three LEDs which obtain an accuracy always below 5 %. 2/9 Doc ID 18457 Rev 2 ILFLH (I > &203 9&. W 7