AP3785T

Document number: DS37552 Rev. 4 - 2

1 of 18

www.diodes.com

September 2015

© Diodes Incorporated

AP3785T

PRIMARY SIDE REGULATED SWITCHING MODE POWER SUPPLY CONTROLLER

Description

The AP3785T is a high performance AC/DC power supply controller

for battery charger and adapter applications. It can meet less than

10

mW 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 AP3785T 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 AP3785T is equipped with both cable drop compensation

function to meet various cables with different lengths and gauges and

adjustable line voltage compensation function.

When AP3785T is used with AP4341 or synchronous rectifier series

(for example APR343 + MOSFET, APR3415, APR34330), better

under-shoot performance and higher conversion efficiency can be

achieved.

The AP3785T has internal over temperature protection for itself, and

also provides dedicated pin for external over temperature protection.

This IC is available in SO-8 package.

Applications



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

and Other Portable Apparatus



Standby and Auxiliary Power Supplies

Pin Assignments

(Top View)

1

2

3

4

8

7

6

5

CS

EM

VCC

OUT

FB

CBC

OTP

GND

SO-8

Features



Primary Side Control for Eliminating Opto-coupler



10mW No-load Input Power



Flyback Topology in DCM Operation



External Adjustable Line Compensation for CC



External Adjustable Cable Compensation for CV



Multiple PWM/PFM Control Mode to Improve Audio Noise and

Efficiency





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



OTP and External Over Temperature Protection (OTP)



Matching

AP4341

with

Schottky

or

APR343/APR3415

Synchronous Rectifier Solution



SO-8 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) 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.