AP3981C PRIMARY SIDE REGULATED POWER SWITCHER Description Pin Assignments (Top View) The AP3981C is a high performance power switchers integrated with a primary side regulation controller and an N-channel power MOSFET. It can be used for battery charger and adaptor applications, GND 8 1 Drain accurate Constant Voltage (CV) and Constant Current (CC) can be achieved without an opto-coupler and secondary control circuitry. FB 2 7 Drain The AP3981C operates in Pulse Frequency Modulation (PFM) mode and peak current Amplitude Modulation (AM) mode to form a fine tune VCC 3 6 Drain frequency curve within the whole power range. Therefore, the AP3981C can achieve high average efficiency and improve audible Drain 5 SOURCE 4 noise. The AP3981C provides comprehensive protections without additional SO-8 circuitry. It contains V over voltage protection, output over voltage CC protection, output under voltage protection, output short circuit protection, cycle-by-cycle current limit, open loop protection, and Applications internal over temperature protection, etc. Routers The AP3981C is available in SO-8 package. Set-Top Box (STB) Power Supply Network Adaptors Features Primary Side Control for Eliminating Opto-Coupler Built-In 650V Power MOSFET 75mW No-Load Input Power 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 Over Voltage Protection (SOVP) Secondary-Side Under Voltage Protection (SUVP) Output Short Circuit Protection (SCP) Transformer Saturation Protection (TSP) via Primary Peak Current Limitation Internal Over Temperature 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 AP3981C Typical Applications Circuit F1 L1 DB1 AC T1 C1 C2 C3 R1 D3 V OUT B1 R15 R16 D3 R13 R17 C12 R18 C13 C14 D1 R2 GND R5 R6 CY1 U1 2 5,6,7,8 FB DRAIN 4 SOURCE 3 VCC R7 R9 AP3981C C10 GND 1 Pin Descriptions Pin Number Pin Name Function GND The ground of the IC 1 Connect to the auxiliary winding through a divider network, used as a multi-function pin to FB realize output voltage sample for CV control, tONS detection for CC control, line voltage sense 2 for line compensation, and FB-negative-protection detection as well. VCC The power supply of the IC 3 SOURCE SOURCE terminal of the integrated MOSFET 4 DRAIN DRAIN terminal of the integrated MOSFET 5, 6, 7, 8 2 of 16 AP3981C June 2019 Diodes Incorporated Document number: DS41619 Rev. 2 - 2 www.diodes.com NEW PRODUCT