AP3987CT

Document number: DS41644 Rev. 2 - 2

1 of 15

www.diodes.com

June 2019

© Diodes Incorporated

AP3987CT

HIGH FREQUENCY PRIMARY SIDE POWER SWITCHER FOR OFF-LINE SMPS

Description

The AP3987CT is a high performance AC/DC power switcher for

battery charger and adapter applications

with a built-in high

performance controller

and a

built-in

650V

high performance

MOSFET. It can meet less than

10mW standby power for “Super Star”

charger criteria. The device uses Pulse Frequency Modulation (PFM)

method to build Discontinuous Conduction Mode (DCM) Flyback

power supplies.

The AP3987CT provides accurate Constant Voltage (CV), Constant

Current (CC) and outstanding dynamic performance without requiring

an opto-coupler. It also eliminates the need of loop compensation

circuitry while maintaining stability.

The AP3987CT is equipped with built-in 0.35V output cable drop

compensation.

The AP3987CT has internal over temperature protection, and also

provides dedicated pin for external over temperature protection.

When the AP3987CT is used with AP4341 or APR3415CT series

synchronous rectifier solution, better under-shoot performance and

higher conversion efficiency can be achieved.

The AP3987CT provides operating frequency dithering function to

improve system EMC performance.

The AP3987CT is packaged in SO-7.

Applications



Adapter/Chargers for Shaver, Cell/Cordless Phones, PDAs, MP3

and Other Portable Apparatus



Standby and Auxiliary Power Supplies

Pin Assignments

(Top View)

FB

OTP

VCC

CS

D

D

GND

1

2

3

4

6

5

7

SO-7

Features



Primary-Side Control for Eliminating Opto-Coupler



10mW No-Load Input Power



Built-In 650V High Performance MOSFET



Flyback Topology in DCM Operation



Built-In 0.35V Cable Compensation for CV



Multiple PWM/PFM Control Mode to Improve Audio Noise and

Efficiency



VCS Jitter to Reduce System EMI



Valley-On for the Higher Efficiency and Better EMI



Multiple Protections:



Over Voltage Protection (OVP)



Output Short Circuit Protection (SCP)



Transformer Saturation Protection (TSP) via Primary

Peak Current Limitation



Internal and External Over Temperature Protection (OTP)



Matching AP4341 with Schottky or APR3415CT Series

Synchronous Rectifier Solution



SO-7 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 https://www.diodes.com/quality/lead-free/ for more information abo

ut 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.