FAN2011/FAN2012 Rev. 1.0.2

1

www.fairchildsemi.com

November 2004

FAN2011/FAN2012

1.5A Low Voltage Current Mode Synchronous PWM Buck

Regulator

Features

I 95% Efficiency, Synchronous Operation

I 4.5V to 5.5V Input Voltage Range

I Up to 1.5A Output Current

I Fixed Frequency 1.3 MHz PWM Operation

I 100% Duty Cycle Low Dropout Operation

I Soft Start

I Excellent Load Transient Response

I 3x3mm 6-lead MLP Package

Applications

I Hard Disk Drive

I Set Top Box

I Point of Load Power

I Notebook Computers

I Communications Equipment

Description

The FAN2011/FAN2012 is a high-efficiency, low-noise synchro-

nous PWM current mode DC-DC converter, designed for low

voltage applications. It provides up to 1.5A continuous load cur-

rent from the 4.5V to 5.5V input. The output voltage is adjust-

voltage divider.

The FAN2011 is always on, while the FAN2012 has an “Enable

Input,” and the device can be put in the shutdown mode, in

which the ground current falls below 1µA.

A current mode control loop with a fast transient response

ensures excellent line and load regulation. The fixed 1.3MHz

switching frequency enables the user to choose a small, inex-

pensive external inductor and capacitor. Filtering is also easily

accomplished with very small components.

Protection features include input under-voltage lockout, short

circuit protection and thermal shutdown. Soft-start limits in-rush

current during start-up conditions.

The device is available in a 3x3mm 6-lead MLP package, mak-

ing it possible to build a 1.5A complete DC/DC converter in a

tiny space on the PCB.

Typical Application

Figure 1. Typical Application

FAN2011

FAN2012

1

2

3

6

5

4

FB

PGND

SW

NC

P1

(AGND)

L1

R2

R1

+5V

4 x 10

µF

3.3

µH

10

µF

10K

Ω

1

2

3

6

5

4

FB

PGND

SW

EN

P1

(AGND)

L1

R2

R1

+5V

4 x 10

µF

3.3

µH

10

µF

10K

Ω