SY8718A1ADC

Applications Note: SY8718A1 High Efficiency,23V,2.0A Synchronous Step Down Regulator For Dimmable LED Driver General Description Features The SY8718A1 is a high efficiency synchronous stepdown LED regulator that achieves up to 2.0A output current. It operates at 1MHz and integrates two very low RDS(ON) power switches to minimize and reduce the external components.  Wide Input Range: 4V-23V  Up to 2.0A Output Current Capability  Low RDS(ON) for Internal Switches High Side/Low Side:125mΩ/75mΩ  Fixed 1MHz Switching Frequency  Cycle by Cycle 3.5A Peak Current Limit for High Side and 2.5A Valley Current Limit for Low Side  High Accuracy for Low Dimming Scale  Output Voltage Discharging  Over Temperature Protection  Compact Package: TSOT23-6 It supports the PWM dimming duty 5%-100% to achieve dimmable LED lighting application. Ordering Information SY8718 □(□□)□ Temperature Code Package Code Optional Spec Code Ordering Number SY8718A1ADC Package type TSOT23-6 Applications  DVR Or NVR(IP Camera) System Application  12VDC Lighting Note ---- Typical Applications L1 5V-12V 4 LX IN 1.5V-9.0V CBS CIN 22µF 3 GND BS 6 RDIM2 1MΩ 1 FB DIM 6.8μH 5 COUT 0.1µF 22µF CDIM1 NC Dimming Signal 2 RDIM1 10KΩ R1 1KΩ RS1 0.067Ω Figure.1 Schematic AN_SY8718A1 Rev.0.9 © 2018 Silergy Corp. Silergy Corp. Confidential-Prepared for Customer Use Only 1 All Rights Reserved. AN_SY8718A1 Pinout (Top View) FB 1 6 BST DIM 2 5 LX GND 3 4 IN (TSOT23-6) Top Mark: Wr xyz, (Device code: Wr; x=year code, y=week code, z= lot number code) Pin Name Pin Number Pin Description FB 1 DIM 2 GND 3 Output current feedback pin. The output current: IOUT =0.1V/ RS Dimming signal input. The PWM dimming duty range: 5%-100% Support the dimming frequency from 20KHz to 500KHz Ground pin IN 4 Input supply pin. Decouple this pin to GND pin with a 1µF ceramic cap LX 5 BST 6 Switching node pin. Connect this pin to the inductor Boot-strap pin. Supply for top side gate driver. Decouple this pin to LX with a 0.1µF ceramic cap Dimming Scale 100% 5% 0% 3% 5% 100% DDIM Figure.2 Ideal dimming curve of SY8718A1 AN_SY8718A1 Rev.0.9 © 2018 Silergy Corp. Silergy Corp. Confidential-Prepared for Customer Use Only 2 All Rights Reserved. AN_SY8718A1 Block Diagram IN Bias&Ref DIM Regulator BST Dimming Curve Conversion Slope Compensation FB Peak Current Detectation 1MHz Clock Driver LX COMPARATOR ERROR AMPLIFIER Fault Detectation Valley Current Detectation GND OTP Figure.3 Functional Block Diagram Absolute Maximum Ratings (Note 1) IN, DIM, FB----------------------------------------------------------------------------------------------- -0.3V to 25V LX ---------------------------------------------------------------------------------------------------------------- -0.3V（*1） to 25V（*2） BST-LX ------------------------------------------------------------------------- --------------------- -0.3V to 4V Power Dissipation, PD @ TA = 25°C TSOT23-6 ------------------------------------------------------- 1.5W Package Thermal Resistance (Note 2) Ɵ JA ------------------------------------------------------------------------------------ ------------------------------- 66°C/W Ɵ JC -------------------------------------------------------------------------------------------------------------------- 15°C/W Junction Temperature Range ------------------------------------------------------------------------------------- -40°C to150°C Lead Temperature (Soldering, 10 sec.) ---------------------------------------------------------------------------- 260°C Storage Temperature Range ------------------------------------------------------------------------------------- -65°C to 150°C (*1) LX Voltage tested down to -3V