AP3128

Document number: DS43487 Rev. 3 - 2

1 of 12

www.diodes.com

September 2021

© Diodes Incorporated

AP3128

HIGH-PERFORMANCE GREEN MODE PWM CONTROLLER

Description

The AP3128 is a peak-current control, multi-mode (QR+CCM) PWM

controller optimized for high performance, low standby power and

cost-effective offline flyback converters.

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

standby power consumption. The minimum switching frequency is set

to avoid audible noise. When the load increases, the IC will enter QR

mode with frequency foldback to improve system efficiency and EMI

performance. The maximum switching frequency about 105kHz is set

to clamp the QR frequency to reduce switching power loss.

Furthermore, the frequency dithering function is built in to reduce EMI

emission.

Internal piecewise linear line compensation ensures constant output

power limit over the entire universal line voltage range.

Comprehensive protection features are included, such as brown-out

protection, cycle-by-cycle current limit (OCP), VCC Overvoltage

Protection (VOVP), Secondary-side Output OVP (SOVP) and UVP

(SUVP), internal OTP, Overload Protection (OLP),

and pins’ fault

protection.

Features



Multi-Mode Control



Quasi-Resonant (QR) Operation at High Line Voltage



Continuous Current Mode (CCM) Operation at Low Line Voltage



Non-Audible-Noise Quasi-Resonant Control



Soft Start During Startup Process



Frequency Fold Back for High Average Efficiency



Constant Over Current Protection



Secondary Winding Short Protection with FOCP



Frequency Dithering for Reducing EMI



Useful Pin Fault Protection:

SENSE Pin Floating

FB/Opto-Coupler Open/Short



Comprehensive System Protection Feature:

VCC Overvoltage Protection (VOVP)

Overload Protection (OLP)



Brown Out Protection (BNO)



Secondary Side OVP (SOVP) and UVP (SUVP)



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



Halogen and Antimony

Free. “Green” Device (Note 3)



For automotive applications requiring specific change

control (i.e. parts qualified to AEC-Q100/101/200, PPAP

capable, and manufactured in IATF 16949 certified facilities),

please contact us or your local Diodes representative.

https://www.diodes.com/quality/product-definitions/

Pin Assignments

(Top View)

1

2

3

4

8

7

6

5

DEM

GATE

VCC

GND

FB

CS

NC

HV

SO-8

Applications



Cell Phone Charger



Power Delivery (PD) Application



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) & 2015/863/EU (RoHS 3) compliant.

2. See https://www.diodes.com/quality/lead-free/

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.