RT8456GE Richtek

RT8456 Isolated Secondary Side LED Lighting Current Controller General Description Features zz z zz Secondary Side LED Current Regulation The RT8456 is an isolated secondary LED current controller zz z zz 4.75V to 48V Operation Range designed specifically for lighting fixtures such as E27, zz z zz High Accuracy 59mV LED Current Threshold Control GU10, T5 and T8. The IC is suitable for applications that zz z zz 0.6mA Operating Current require power line isolation for safety and reliability, high zz z zz Programmable LED Current conversion efficiency, as well as high LED current accuracy. zz z zz Output Over Voltage Protection The RT8456 contains 1) a constant current regulating zz z zz Small SOT-23-6 Package amplifier with 59mV threshold used to program the LED zz z zz RoHS Compliant and Halogen Free string current with a simple resistor to within 5% LED current accuracy 2) an over voltage comparator to protect Applications the output when LED string is open or broken 3) and an z Isolated LED Lighting Fixtures opto-coupler driver to control the primary side of the z E27/GU10/T5/T8 transformer to complete the system loop. The RT8456 is offered in a small SOT-23-6 package. Pin Configurations (TOP VIEW) Ordering Information VCC OUT CP RT8456 6 5 4 Package Type 23 E : SOT-23-6 Lead Plating System CN GND OVP G : Green (Halogen Free and Pb Free) SOT-23-6 Note : Richtek products are : RoHS compliant and compatible with the current require- ments of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. Marking Information EM= : Product Code EM=DNN DNN : Date Code Copyright 2013 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS8456-05 April 2013 www.richtek.com 1RT8456 Function Block and Typical Application Circuit D1 VOUT Optocoupler VCC R1 R LED RT8456 LED String 2.5V OUT C VCC CV Secondary - side winding + C VC1 R VC1 OVP 59mV CC - R IC1 R2 + C IC1 CP CN GND R CN R SENSE Functional Pin Description Pin No. Pin Name Pin Function Non-inverting Input of the CC Regulating Amp. It has a 59mV offset from the CP pin. 1 CN The CN pin should be connected to theCurrent I node of the current sensing resistor, R . SENSE 2 GND Ground of the RT8456 and secondary side. 3 OVP Output Over Voltage Protection Pin with Threshold of 2.5V. Inverting Input of the CC Regulating Amp. It has a 59mV offset from CN pin. CP pin 4 CP connects to a resistor to set LED current. Open-collector Output. Connects this pin to an opto-coupler with a current limiting 5 OUT resistor. Supply Voltage Input. A 0.1F bypass capacitor should be connected between VCC 6 VCC and GND. Copyright 2013 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS8456-05 April 2013 2