WIDE INPUT 2A STEP-DOWN CONVERTER

2007-1-4

1/10

FSP3129

PIN ASSIGNMENT

(Top View)

PIN DESCRIPTION

Pin Number Pin Name

Pin Description

1

BS

Bootstrap. This pin acts as the positive rail for the high-side switch’s gate driver.

Connect a 10nF between this pin and SW.

2

IN

Input Supply. Bypass this pin to G with a low ESR capacitor. See Input Capacitor in

Application Information section.

3

SW

Switch Output. Connect this pin to the switching end of the inductor.

4

G

Ground.

5

FB

Feedback Input. The voltage at this pin is regulated to 1.222V. Connect to the resistor

divider between the output and ground to set output voltage.

6

COMP

Compensation Pin. See Compensation Technique in Application information section.

7

EN

Enable Input. Drive higher than 1.3V or unconnected to enable the IC. Drive lower than

0.7V to disable the IC. The IC is in 6µA low current shutdown mode and the output is

discharged through the Low-Side Power Switch. This pin has a small internal pull up

current to a high level voltage when pin is not connected.

8

N/C

Not Connected.

TYPICAL APPLICATION

T

FT LCD Monitors or Televisions and HDTV

Portable DVD Players

Car-Powered or Battery-Powered Equipment

Set-Top Boxes

Telecom Power Supplies

DSL and Cable Modems and Routers

G

N/C

EN

COMP

FB

8

7

6

5

1

2

3

4

BS

IN

SW

GENERAL DESCRIPTION

The FSP3129 is a current-mode step-down DC/DC

converter that generates up to 2A output current at

400kHz switching frequency. The device can

operate with input voltage up to 30V.

Consuming only 6µA in shutdown mode, the

FSP3129 is highly efficient with peak efficiency at

95% when in operation. Protection features include

cycle-by-cycle current limit, thermal shutdown, and

frequency fold back at short circuit.

The FSP3129 is available in SOP8L package and

requires very few external devices for operation.

FEATURES

2A Output Current

Up to 95% Efficiency

Up to 30V Input Range

6µA Shutdown Supply Current

400kHz Switching Frequency

Adjustable Output Voltage

Cycle-by-Cycle Current Limit Protection

Thermal Shutdown Protection

Frequency Fold Back at Short Circuit

Stability with Wide Range of Capacitors,

Including Low ESR Ceramic Capacitors

SOP8L Package