Description

3255 products are 280 kHz switching regulators with a

high efficiency, 1.5 A integrated switch. These parts oper-

ate over a wide input voltage range, from 2.7 V to 30 V.

The flexibility of the design allows the chips to operate in

most power supply configurations, including boost, flyback,

forward, inverting, and SEPIC. The ICs utilize current

mode architecture, which allows excellent load and line reg-

ulation, as well as a practical means for limiting current.

Combining high frequency operation with a highly inte-

grated regulator circuit results in an extremely compact

power supply solution. The circuit design includes provi-

sions for features such as frequency synchronization, shut-

down, and feedback controls for either positive or negative

voltage regulation.

Application

Boost Regulators

CCFL Backlight Driver

Laptop Computer Supplies

Multiple Output Flyback Supplies

Inverting Supplies

TFT LCD Bias Supplies

TYPICAL APPLICATION CIRCUITS

Features

Integrated Power Switch: 1.5 A Guaranteed

Input Voltage Range: 2.7 V to 30 V

High Frequency Allows for Small Components

Minimum External Components

Easy External Synchronization

Built in Overcurrent Protection

Frequency Foldback Reduces Component

Stress During an Overcurrent Condition

Thermal Shutdown with Hysteresis

Regulates Either Positive or Negative Output

Voltages

Shut Down Current: 50 µA Maximum

Wide Temperature Range Commercial

Commercial Grade : 0 to 70°C (3255)

3255

V

C

FB

Test

SS

V

SW

PGND

AGND

V

CC

1

2

3

4

5

6

7

8

R2

3.72K

C1

0.01µF

SS

3.3V

R1

5k

R3

1.28k

C2

22µF

L1

22µH

D1

MBRS120T3

V

OUT

5V

C3

22µF

+

+

FC3255 1.5A PWM Switching Regulators