AP3988

Document number: DS36722 Rev. 4 - 2

3 of 12

www.diodes.com

June 2014

© Diodes Incorporated

AP3988

A Product Line of

Diodes Incorporated

Pin Descriptions

Pin Number

Pin Name

Function

1

CPC

This pin connects a capacitor to GND for output cable compensation

2

FB

The voltage feedback from auxiliary winding

3

VCC

This pin receives rectified voltage from the auxiliary winding of the transformer

4

CS

Current sense for primary side of transformer

5, 6

C

This pin is connected with an internal power BJT’s collector

7

GND

This pin is the signal reference ground

Functional Block Diagram

Regulator

&

Bias

OVP

OCkP

OTP

PFM

UVLO

CV_ctrl

PFM

Driver

R Q

S

R

Q

S

FB

CS

CPC

VCC

CS

GND

Constant Voltage Control

Cable Compensation

Constant Current

Control

0.05V

3

4

7

1

2

COMP

Peak Current Control

LEB

Frequency Dither

Dynamic

Response

Pro

Dyn

Shutdown

Pre_Shutdown

Line

Comp.

Detector

OSC

UV

UV

Vload

Vally

ON

Vload

CC_ctrl

Max Tonp

Rcs Short

Output Short

LL

NL

CPC

Detect

Pulse

(LL+NL)Bar

NL

Vload

UV

CV_M

DetectON

DetectON

LL

Vload

C

5, 6