RT2808A

2

DS2808A-00

November 2012

www.richtek.com

©

Copyright

2012 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

Functional Pin Description

Function Block Diagram

Pin No.

Pin Name

Pin Function

1

BOOT

Bootstrap Input for High Side Gate Driver. Connect a 10nF or greater capacitor

from SW to BOOT to power the high side switch.

2, 3

NC

No Internal Connection.

4

FB

Feedback Input. The feedback threshold is 1.222V.

5

EN

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

higher than 1.4V to turn on the regulator, lower than 0.4V to turn it off. For

automatic startup, leave EN unconnected.

6,

9 (Exposed Pad)

GND

Ground. The exposed pad must be soldered to a large PCB and connected to

GND for maximum power dissipation.

7

VIN

Power Input. A suitable large capacitor should be connected from the VIN to

GND to eliminate noise on the input to the IC.

8

SW

Switch Node. Note that a capacitor is required from SW to BOOT to power the

high side switch.

Pin Configurations

(TOP VIEW)

SOP-8 (Exposed Pad)

SW

BOOT

NC

FB

NC

EN

VIN

GND

2

3

4

5

8

7

6

GND

9

S

Q

R

Driver

Bootstrap

Control

-

+

Current Sense

Amplifier

Current

Comparator

Oscillator

500kHz

Ramp

Generator

Regulator

Reference

+

-

12k

Error

Amplifier

30pF

400k

13pF

SW

BOOT

FB

EN

VIN

GND

+

-