AP3981D2

Typical Applications Circuit

AC

R1

C13

T 1

D3

F1

R17

C3

C12

CY1

GND

DRAIN

SOURCE

VCC

AP3981D2

U1

FB

VOUT

GND

C2

L1

5,6,7,8

4

1

R5

R6

2

R18

R2

D1

C1

DB1

B1

3

D3

R13

R16

R15

C10

R7

R9

C14

Pin Descriptions

Pin Number

Pin Name

Function

1

GND

IC ground

2

FB

Connect to the auxiliary winding through a divider network. Used as a multi-function pin to realize

output voltage sample for CV control, tons detection for CC control, line voltage sense for line

compensation, and FB-negative-protection detection.

3

VCC

IC power supply

4

SOURCE

SOURCE terminal of the integrated MOSFET

5, 6,7,8

DRAIN

DRAIN terminal of the integrated MOSFET

AP3981D2

Document number: DS41421 Rev. 2 - 2

2 of 16

www.diodes.com

May 2019

© Diodes Incorporated