5

Mar -07 Rev N

SP766 Wide Input Voltage Range 3A, 600kHz Buck Regulator

© 2007 Sipex Corporation

PIN DESCRIPTION

Pin #

Pin

Name

Description

1-4

PGND Groundconnectionforthesynchronousrectifier.

5,9,

GroundPin.ThecontrolcircuitryoftheICandlowerpowerdriverarereferencedtothis

6

VFB

FeedbackVoltageandShortCircuitDetectionpin.Itistheinvertinginputofthe

Error Amplifier and serves as the output voltage feedback point for the Buck

Converter.Theoutputvoltageissensedandcanbeadjustedthroughanexternal

resistordivider.WheneverVFBdrops0.25Vbelowthepositivereference,ashort

circuitfaultisdetectedandtheICentershiccupmode.

7

COMP

OutputoftheErrorAmplifier.Itisinternallyconnectedtotheinvertinginputofthe

PWMcomparator.Anoptimalfiltercombinationischosenandconnectedtothis

pinandeithergroundorVFBtostabilizethevoltagemodeloop.

8

SS

SoftStart.ConnectanexternalcapacitorbetweenSSandGNDtosetthesoftstart

ratebasedonthe10µAsourcecurrent.TheSSpinisheldlowviaa1mA(min)

currentduringallfaultconditions.

0

ISN

Currentsensenegativeinput.Rail-to-railinputforovercurrentdetection.



ISP

Currentsensepositiveinput.Rail-to-railinputforovercurrentdetection.

2

SWN LowersupplyrailfortheGHhigh-sidegatedriver.Connectthispintotheswitching

nodeascloseaspossibletopins23-27.Donotconnectthispintopins14–16.

3

VINP InputconnectiontothehighsideN-channelMOSFET.

14-16,

23-26

LX

7

BST

Highsidedriversupplypin.ConnectBSTtotheexternalboostdiodeandcapacitor

as shown in the TypicalApplication Circuit on page 1.The high side driver is

connectedbetweenBSTpinandSWNpin.

18

VIN

2

UVIN

tosetminimumoperatingvoltage.Useresistorvaluesbelow20kΩtooverride

internalresistordivider.

22

VCC Outputofinternalregulator.MaybeexterinallybiasedifVin<5V.

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

BOTTOM VIEW

Heatsink Pad 1

Connect to Lx

Heatsink Pad 2

Connect to GND

Heatsink Pad 3

GND

COMP

SWN

LX

LX

LX

LX

BST

LX

LX

LX

DFN PACKAGE

7mm x 4mm (Option 2)

SP7661

VINP

SS

ISN

ISP

GND

GND

GND

Pin 27

Pin 28

Pin 29