AP3301

Document number: DS38018 Rev. 4 - 2

1 of 16

www.diodes.com

June 2016

© Diodes Incorporated

AP3301

QUASI-RESONANT PWM CONTROLLER

Description

The AP3301 is a peak-current control, Quasi-Resonant (QR) PWM

controller which is optimized for high performance, low standby power

and cost effective offline flyback converters.

At no load or light load, the IC will enter the burst mode to minimize

standby power consumption. The minimum switching frequency

(about 20kHz) is set to avoid the audible noise. At medium load, the

IC will enter valley lock QR mode with frequency foldback to improve

system efficiency and EMI performance. The maximum switching

frequency (about 120kHz) is set to clamp the QR frequency to

improve efficiency. At low line input & heavy load, when switching

frequency decreases below 62KHz with output load increasing, the IC

will enter CCM mode with fixed switching frequency of 62kHz to

optimize low line power conversion efficiency. Furthermore, the

frequency dithering function is built in to reduce EMI emission.

Internal slope compensation allows more stable peak-current mode

control over wide range of input voltage and load conditions. Internal

piecewise linear line compensation ensures constant output power

limit over entire universal line voltage range.

Comprehensive protection features are included, such as brown out

protection, cycle-by-cycle current limit (OCP), VCC Over Voltage

Protection (VOVP), Secondary-Side Output OVP (SOVP), internal

OTP, Over Load Protection (OLP) and pins’ fault protection.

Features



Very Low Start-up Current



Multi-Mode Control



Quasi-Resonant Operation with Valley Lock



Fixed Frequency CCM Operation at Low Line Heavy Load



Non-Audible-Noise Quasi-Resonant Control



Internal Slope Compensation



Soft Start During Startup Process



Frequency Fold Back for High Average Efficiency



Secondary Winding Short Protection with FOCP



Frequency dithering for Reducing EMI



VCC Maintain Mode



Useful Pin Fault Protection:

SENSE Pin Floating

FB/Opto-coupler Open/Short



Comprehensive System Protection Feature:

VCC Over Voltage Protection (VOVP)

Over Load Protection (OLP)



Brown Out Protection (BNO)



Secondary Side OVP (SOVP)



Mini Size Package of SOT26



Totally Lead-free & Fully RoHS Compliant (Notes 1 & 2)



Halogen and Antimony Free. “Green” Device (Note 3)

Pin Assignments

(Top View)

SOT26

Applications



Switching AC-DC Adapter/Charger



ATX/BTX Auxiliary Power



Set-Top Box (STB) Power Supply



Open Frame Switching Power Supply

Notes:

1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.

2. See http://www.diodes.com/quality/lead_free.html for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green"

and Lead-free.

3. Halogen- and Antimony-

free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and

<1000ppm antimony compounds.

1

2

3

4

5

Pin 1 Mark

6

GND

FB

DEM

GATE

VCC

SENSE