AP3981B PRIMARY SIDE REGULATED POWER SWITCHER Description Pin Assignments (Top View) The AP3981B 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 achieved without an opto-coupler and secondary control circuitry. 1 NC 7 GND The AP3981B operates in Pulse Frequency Modulation (PFM) mode and peak current Amplitude Modulation (AM) mode to form a fine tune 2 FB frequency curve within the whole power range. Therefore, the AP3981B can achieve high average efficiency and improve audible noise. 3 6 DRAIN VCC The AP3981B provides comprehensive protections without additional circuitry. It contains V over voltage protection, output over voltage CC SOURCE DRAIN 4 protection, output under voltage protection, output short circuit 5 protection, cycle-by-cycle current limit, open loop protection, and internal OTP, etc. The AP3981B is available in SO-7 package. SO-7 Features Primary-Side Control for Eliminating Opto-Coupler Applications Built-In 650V Power MOSFET Routers 75mW No-Load Input Power Set-Top Box (STB) Power Supply Flyback Topology in DCM Operation Network Adaptors 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-7 Package The Recommended Output Power is up to 7.5W 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 AP3981B Typical Applications Circuit F1 L1 AC DB1 T1 C1 C2 C3 R1 D3 V OUT B1 R15 R16 D3 R18 R17 C12 C14 C13 R13 D1 R2 GND R5 R6 CY1 U1 2 5,6 FB DRAIN 4 SOURCE 3 VCC R7 R9 AP3981B C10 GND 7 Pin Descriptions Pin Number Pin Name Function NC No Connection 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, t detection for CC control, line voltage sense for line 2 ONS 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 GND The ground of the IC 7 2 of 17 AP3981B May 2019 Diodes Incorporated Document number: DS41422 Rev. 2 - 2 www.diodes.com NEW PRODUCT