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3I13N-Rev.P001

2.4A/32V Synchronous Rectified

Step-Down Converter

EC3278

Pin Configurations

Figure 2 Pin Configuration of EC3278(Top View)

Pin Description

Pin Number

Pin Name

Description

1

BS

High-Side Gate Drive Boost Input. BS supplies the drive for the high-side N-Channel

MOSFET switch. Connect a 0.01µF or greater capacitor from SW to BS to power the

high side switch.

2

IN

Power Input. IN supplies the power to the IC, as well as the step-down converter

switches. Drive IN with a 4.75V to 32V power source. Bypass IN to GND with a

suitably large capacitor to eliminate noise on the input to the IC. See Input Capacitor.

3

SW

Power Switching Output. SW is the switching node that supplies power to the output.

Connect the output LC filter from SW to the output load. Note that a capacitor is

required from SW to BS to power the high-side switch.

4

GND

Ground.

5

FB

Feedback Input. FB senses the output voltage to regulate that voltage. Drive FB

with a resistive voltage divider from the output voltage. The feedback threshold

is 0.923V. See Setting the Output Voltage.

6

COMP

Compensation Node. COMP is used to compensate the regulation control loop.

Connect a series RC network from COMP to GND to compensate the regulation

control loop. In some cases, an additional capacitor from COMP to GND is

required. See Compensation Components.

7

EN

Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to

turn on the regulator, drive it low to turn it off. Pull up with 100k

Ω resistor for

automatic startup.

8

SS

Soft-Start Control Input. SS controls the soft start period. Connect a capacitor from SS

to GND to set the soft-start period. A 0.1µF capacitor sets the soft-start period to 15ms.

To disable the soft-start feature, leave SS unconnected.