RT8476GS

RT8476 Two-Stage Hysteretic LED Driver Controller General Description Features zz z zz Two-Stage Topology (Boost + Buck) The RT8476 is a two-stage controller with dual gate drivers zz z zz Wide Input Voltage Range : 4.5V to 40V consist of a Boost converter (first stage) and a Buck zz z zz Adjustable Peak Input Current Control converter (second stage). The advantage of the two-stage zz z zz Adjustable Boost Output Voltage topology is highly compatible with ET (Electronic zz z zz Independent Dual Stage Function Transformer) in MR16 / AR111 lighting market field zz z zz Adjustable LED Current with 5% LED Current applications. Accuracy The first stage is a Boost converter for constant voltage zz z zz Input Under Voltage Lockout Detection output with inductor peak current over current protection. zz z zz Thermal Shutdown Protection The second stage is a Buck converter for constant output zz z zz SOP-8 and SOP-8 (Exposed Pad) Packages current by typical constant peak current regulation. zz z zz RoHS Compliant and Halogen Free The RT8476 is equipped with dual output gate drivers for external power MOSFETs, suitable for higher power Ordering Information applications. RT8476 Package Type The RT8476 is available in the SOP-8 and SOP-8 (Exposed S : SOP-8 pad) packages. SP : SOP-8 (Exposed Pad-Option 2) Lead Plating System Applications G : Green (Halogen Free and Pb Free) Note : z MR16 Lighting Richtek products are : z Signage and Decorative LED Lighting RoHS compliant and compatible with the current require- z Architectural Lighting ments of IPC/JEDEC J-STD-020. z High Power LED Lighting Suitable for use in SnPb or Pb-free soldering processes. z Low Voltage Industrial Lighting z Indicator and Emergency Lighting z Automotive LED Lighting Simplified Application Circuit L1 D6 R SENSE C OUT R4 RT8476 D1 D2 OVP VCC VL R5 AC 12V ISN LED+ M1 C IN CREG D7 VN C6 GATE1 C3 L2 LED- CS D3 D4 M2 R6 GATE2 GND Copyright 2013 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS8476-00 April 2013 www.richtek.com 1RT8476 Marking Information Pin Configurations RT8476GS (TOP VIEW) RT8476GS : Product Number 8 GATE1 GATE2 RT8476 YMDNN : Date Code 2 7 CS CREG GSYMDNN 3 6 OVP VCC 4 5 GND ISN RT8476GSP RT8476GSP : Product Number SOP-8 RT8476 YMDNN : Date Code GSPYMDNN 8 GATE1 GATE2 2 7 CS CREG GND 3 6 OVP VCC 9 4 5 GND ISN SOP-8 (Exposed Pad) Functional Pin Description Pin No. Pin Name Pin Function SOP-8 SOP-8 (Exposed Pad) 1 1 GATE1 Gate Driver Output for External MOSFET Switch in the First Stage. 2 2 CS Current Sense Input for External MOSFET Switch. 3 3 OVP Over Voltage Protection Sense Input. 4, Ground. The exposed pad must be soldered to a large PCB and 4 GND 9 (Exposed Pad) connected to GND for maximum power dissipation. 5 5 ISN LED Current Sense Amplifier Negative Input. Supply Voltage Input. For good bypass, place a ceramic capacitor 6 6 VCC near the VCC pin. Internal Regulator Output. Place an 1 F capacitor between the 7 7 CREG CREG and GND pins. Gate Driver Output for External MOSFET Switch in the Second 8 8 GATE2 Stage. Copyright 2013 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS8476-00 April 2013 2