AP3301
QUASI-RESONANT PWM CONTROLLER
Description
Pin Assignments
NEW PRODUCT
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.
(Top View)
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.
Pin 1 Mark
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)
Notes:
GND
1
6
GATE
FB
2
5
VCC
DEM
3
4
SENSE
SOT26
Applications
Switching AC-DC Adapter/Charger
ATX/BTX Auxiliary Power
Set-Top Box (STB) Power Supply
Open Frame Switching Power Supply
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
