AP3988

Document number: DS36722 Rev. 4 - 2

1 of 12

www.diodes.com

June 2014

© Diodes Incorporated

AP3988

A Product Line of

Diodes Incorporated

CPC

FB

VCC

CS

C

C

GND

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PRIMARY SIDE POWER SWITCHER FOR OFF-LINE SMPS

Description

The AP3988 is a performance enhanced power switcher for power

supplies with better conversion efficiency, better voltage & current

accuracy, and improved protection functions. Typical applications

include charger, adapter for ADSL, home appliance power supply,

LED lighting power supply and PC auxiliary power supplies. The

controller regulates the output voltage and current in the primary

side by piece-wise Pulse Frequency Modulation (p-PFM) in

discontinuous conduction mode (DCM). The system operating

frequency reduces linearly from heavy load to light load in each

interval of the p-PFM, and enters constant current mode when the

load current equals to the maximum system output current.

The AP3988 provides operating frequency dithering function to

improve EMC performance of power supply. It also has built-in

fixed cable voltage drop compensation (5% of nominal system

output voltage) and adjustable line voltage compensation.

The AP3988 solution has fewer component number, smaller size,

and lower total cost.

The AP3988 is packaged in SO-7.

Features



Primary

Side

Control

for

Eliminating

Opto-coupler

and

Secondary CV/CC Control Circuitry





Low Start-up Current: 0.2

A (Typ.)



Internal Output Cable Voltage Drop Compensation



Hiccup Function to Improve Short Circuit Protection



Better Over Voltage Protection



Better Over Temperature Protection



Low Total Cost Solution



Output Power Range (Note 1): for 5.5W Adapter



Totally Lead-free & Fully RoHS Compliant (Note 2 & 3)



Halogen and Antimony Free.

“Green” Device (Note 4)

Pin Assignments

(Top View)

SO-7

Applications



Adapters



Set Top Boxes



Appliances

Notes:

1. Typical continuous power in a non-ventilated enclosed adapter measured at +50°C ambient.

2. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.

3. 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.

4. Halogen- and Antimony-

free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and

<1000ppm antimony compounds.