US4651S

LINEAR INTEGRATED CIRCUIT

UNISONICTECHNOLOGIESCO.,LTD

2 of 9

www.unisonic.com.tw

QW-R129-003.B



MARKING



PIN CONFIGURATION

GND

FB

NC

DRAIN

NC

CS

1

2

3

4

8

7

6

5

NC



PIN DESCRIPTION

PIN NO.

PIN NAME

PIN TYPE

DESCRIPTION

1

P

Power supply.

2

GND

P

Ground.

3, 5, 7

NC

No Connection

4

CS

I

Current sense input pin. Connected to MOSFET current sensing resistor

node.

6

DRAIN

O

Connected the primary lead of the transformer.

8

FB

I

Feedback input pin. The PWM duty cycle is determined by voltage level

into this pin and CS pin input.



BLOCK DIAGRAM

DRAIN

FB

PWM COMP

OCP

UVLO

Reference voltage

Burstmode

GND

Latch

S

R

Q

Q

CS

Driver

LEB

Slope Compensation

Constant Power Limit

OTP

Logic

Control

OVP

8

1

6

4

3/5/7

2

Oscillator

Frequency

Hopping

NC

UVLO

M1

M2