AP3981D2 PRIMARY SIDE REGULATED POWER SWITCHER Description Pin Assignments (Top View) The AP3981D2 is a high-performance power switcher integrated with a primary-side regulation controller and an N-channel power MOSFET. It can be used for battery charger and adaptor applications. Accurate constant voltage (CV) and constant current (CC) can be GND 1 8 DRAIN achieved without an optocoupler and secondary control circuitry. FB 2 7 DRAIN The AP3981D2 operates in pulse frequency modulation (PFM) mode and peak current amplitude modulation (AM) mode to form a fine-tune frequency curve within the whole power range. Therefore, AP3981D2 VCC 3 6 DRAIN can achieve high-average efficiency and improve audible noise. SOURCE 5 DRAIN 4 The AP3981D2 provides comprehensive protections without additional circuitry. It contains V overvoltage protection, output CC overvoltage protection, output undervoltage protection, output short- SO-8 circuit protection, cycle-by-cycle current limit, open-loop protection, and internal OTP, etc. The AP3981D2 is available in SO-8. Features Applications Primary Side Control for Eliminating Optocoupler Routers Built-In 650V Power MOSFET of AP3981D2 Set-Top Box (STB) Power Supply 75mW No-Load Input Power Network Adaptors Flyback Topology in DCM Operation External Adjustable Line Compensation for CC Fixed Internal Cable Compensation Multiple Segment AM/PFM Control Mode to Improve Audio Noise and Efficiency Frequency Jitter to Improve System EMI Capacitive Load Start-Up Capability Valley-On for the Higher Efficiency and Better EMI Behavior Multiple Protections: Secondary-Side Overvoltage Protection (SOVP) Secondary-Side Undervoltage Protection (SUVP) Output Short-Circuit Protection (SCP) Transformer Saturation Protection (TSP) via Primary Peak Current Limitation Internal Overtemperature Protection (OTP) SO-8 Package Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2) Halogen and Antimony Free. Green Device (Note 3) Notes: 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS), 2011/65/EU (RoHS 2) & 2015/863/EU (RoHS 3) compliant. 2. See AP3981D2 Typical Applications Circuit F1 L1 DB1 AC T 1 C1 C2 C3 R1 D3 V OUT B1 D3 R16 R15 R13 R17 C12 R18 C13 C14 R2 D1 GND R5 R6 CY1 U1 2 5,6,7,8 FB DRAIN 4 SOURCE 3 VCC R7 R9 AP3981D2 C10 GND 1 Pin Descriptions Pin Number Pin Name Function GND IC ground 1 Connect to the auxiliary winding through a divider network. Used as a multi-function pin to realize FB output voltage sample for CV control, tons detection for CC control, line voltage sense for line 2 compensation, and FB-negative-protection detection. VCC IC power supply 3 SOURCE SOURCE terminal of the integrated MOSFET 4 DRAIN DRAIN terminal of the integrated MOSFET 5, 6,7,8 2 of 16 AP3981D2 May 2019 Diodes Incorporated Document number: DS41421 Rev. 2 - 2 www.diodes.com