AP3984

Document number: DS37655 Rev. 3 - 2

1 of 15

www.diodes.com

December 2016

© Diodes Incorporated

AP3984

PRIMARY SIDE POWER SWITCHER FOR OFF-LINE SMPS

Description

The AP3984 is a 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 and PC auxiliary power supplies.

The AP3984 with built in BJT, regulates the output voltage and current

in the primary side by piece-wise pulse frequency modulation (p-PFM)

and primary current peak amplitude modulation (AM) 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

operating frequency is fixed at medium load by varying primary current

peak amplitude.

The AP3984 has good transient characteristics in combination with

the secondary side IC like AP4341/AP43410. Typically, minimal

voltage of 4.3V at PCB side can be achieved for dynamic test of 5V

application system.

The AP3984 provides operating frequency dithering function to

improve EMC performance of power supply. The AP3984 also has

programmable cable voltage drop compensation function by external

resistor.

The AP3984 is packaged in SO-7.

Features



Primary Side Control for Eliminating Opto-coupler



Built-in 700V BJT



Excellent Transient Characteristics



High Voltage and Super-speed Start up



External Adjustable Output Cable Voltage Drop Compensation



Ultra-low No-load Power Consumption(<10mW)



Multiple PWM/PFM Mode to Improve Audio Noise and Efficiency



Valley-on for Higher Efficiency and Better EMI



Multiple Protections:



Over Voltage Protection (OVP)



Output Short Circuit Protection (SCP)



Over Temperature Protection (OTP)



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



Halogen and Antimony Free.

“Green” Device (Note 3)

Pin Assignments

(Top View)

1

2

3

4

7

6

5

FB

CBC

VCC

CS

GND

C

C

SO-7

Applications



Adapters



Set Top Boxes



Auxiliary Supplies



Appliances

Note:

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.