AP3771

Document number: DS37281 Rev. 1 - 2

3 of 11

www.diodes.com

May 2014

© Diodes Incorporated

AP3771

A Product Line of

Diodes Incorporated

Pin Descriptions

Pin Number

Pin Name

Function

1

GATE

The GATE pin is used to turn on and turn off the power switch. When turning on the power

switch, the GATE pin will keep the gate voltage of the power MOSFET to 10V. When

turning off the power switch, the resistance between the GATE and GND will become

40

Ω

2

GND

The GND pin is the ground of the IC. When the power MOSFET is turned off, a fast reverse

sinking current to the GATE of MOSFET will flow out from this pin. Attention should be paid

to in the PCB layout

3

VCC

The VCC pin supplies the power for the IC. In order to get the correct operation of the IC, a

capacitor with low ESR should be placed as close as possible to the VCC pin

4

CS

The CS is the current sense pin of the IC. The IC will turn off the power MOSFET according

to the voltage on the CS pin. When the power MOSFET is on, a current is output from the

CS pin which is proportional to the line voltage to realize the function of line compensation

5

CPC

A capacitor more than 50nF should be connected to this pin. The voltage of CPC pin is

linear to load of the system and it is used for the functions of cable voltage drop

compensation and audio noise suppression

6

FB

The CV and CC regulation are realized based on the voltage sampling of this pin

Functional Block Diagram

Regulator

&

Bias

OVP

&

OCKP

PFM

TONS

UVLO

UVLO

CV_ctrl

PFM

Driver

R

Q

S

R

Q

S

CC_ctrl

FB

CS

CPC

VCC

GATE

GND

Cable

Compensation

Constant Voltage

Control

Constant Current

Control

Tonsec

Detector

0.1V

VFB

4

3

1

2

5

6

VREF1

COMP

EA

Peak Current

Control& LEB

TONS

Dynamic

Response

Pro

Dyn

CC_ctrl

Audio noise

Suppression

VREF2

Shutdown

Line

Compensation

Dmin

R

Q

S

SCP

VCC

OVP

R

Q

S

UVLO