Description
The AP3771 is a high performance AC/DC power supply controller for
battery charger and adapter applications. The device uses Pulse
Frequency Modulation (PFM) method to build discontinuous
conduction mode (DCM) flyback power supplies.
The AP3771 provides accurate constant voltage, constant current
(CV/CC) regulation without requiring an opto-coupler and the
secondary control circuitry. It also eliminates the need of loop
compensation circuitry while maintaining good stability. The AP3771
can achieve excellent regulation and high average efficiency, yet
meets no-load consumption less than 30mW. It can also achieve
excellent dynamic performance while maintaining 30mW standby
power with AP4340.
The AP3771 has a built-in fixed cable voltage drop compensation
function. The cable compensation voltage is set as 7% and 3% of the
rated output voltage. It also has an adjustable built-in line
compensation function to achieve tight CC.
The AP3771 drives MOSFET to achieve the high switching frequency
and high efficiency.
The AP3771 is available in SOT26 package.

Features
Primary Side Control for Tight Constant Current and Constant
Voltage
30mW No-load Input Power
Excellent Dynamic Performance with AP4340 (For 5V
Application)
MOSFET Driving
Proprietary Adjustable Line Compensation for CC Variation
Constant and Built-in 7% and 3% Voltage Drop Compensation
Enhanced Audio Noise Suppression
Open Circuit Protection
Over Voltage Protection
Short Circuit Protection
SOT26 Package
Totally Lead-free & Fully RoHS Compliant (Notes 1 & 2)
Halogen and Antimony Free. “Green” Device (Note 3)

Applications
Adapters/Chargers for Cell/Cordless Phones, PDAs, MP3 and
Other Portable Devices
LED Driver
Standby and Auxiliary Power Supplies