NOT RECOMMENDED FOR NEW DESIGN - NO ALTERNATE PART AL1678-20B/10B/08B UNIVERSAL, 500V BUCK LED DRIVER Description Pin Assignments The AL1678-20B/10B/08B is a universal AC input (85 to 277 VAC), (Top View) high efficiency and high accuracy Buck LED driver. The AL1678- 20B/10B/08B topology provides accurate constant current over line and load regulation with tight tolerance 3%, operating at boundary conduction mode (BCM) to ease in EMI/EMC qualification and testing 7 OUT 1 Drain to meet the latest regulatory laws. VCC 2 The AL1678-20B/10B/08B single buck stage system works with a single winding inductor and high voltage MOSFET included, ROVP LC 3 6 therefore, can use fewer external components and create a low bill of material (BOM) cost solution. The AL1678-20B/10B/08B has rich 5 CS GND 4 protection features to enhance the system safety and reliability. It has thermal fold back function, which can reduce the output current when the drivers temperature is higher than the setting value. SO-7 The AL1678-20B/10B/08B is available in SO-7 package. Applications Features Retrofit LED Lamps > 90% Efficiency Valley Switching to Achieve Low Switching Loss High Voltage DC-DC LED Driver General Purpose Constant Current Source Universal 85 to 277 VAC Input Range Internal MOSFET up to 500V Tight Current Sense Tolerance: 3% Low Start-Up Current: 170A Low Operation Current: 100A (Static) Single Winding Inductor Internal Protections Under Voltage Lock Out (UVLO) Leading-Edge Blanking (LEB) Output Open/Short Protection Open-Load and Reload Detection Thermal Fold-Back Function Over Temperature Protection (OTP) SO-7 Package Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2) Halogen and Antimony Free. Green Device (Note 3) For automotive applications requiring specific change control (i.e. parts qualified to AEC-Q100/101/200, PPAP capable, and manufactured in IATF 16949 certified facilities), please contact us or your local Diodes representative. AL1678-20B/10B/08B Pin Descriptions Pin Number Pin Name Function 1 OUT Internal power MOSFETs source 2 VCC Power supply for the device 3 ROVP Setting the open voltage of the output 4 GND Ground 5 CS Current sensing 6 LC Line compensation pin 7 Drain Internal high voltage MOSFETs drain Functional Block Diagram Drain VCC 7 2 STOP Fault UVLO V CC VCC Clamp Management Management OTP 3 1 ROVP OUT toff Detection VCC (ZCD) Output OVP OVP Q S R 5 Constant LEB CS Current Control 6 LC STOP Max ton Limit 4 GND 2 of 13 AL1678-20B/10B/08B April 2020 Diodes Incorporated www.diodes.com Document number: DS37637 Rev. 2 - 3