NX2601

6

Rev. 2.3

12/01/06

PIN DESCRIPTIONS

PIN #

PIN SYMBOL

PIN DESCRIPTION

This pin is connected to the drain of the external low side MOSFET and is the

input of the over current protection(OCP) comparator. An internal current source

which equals 1.25V divided by Rt resistor is flown to the external resistor which

sets the OCP voltage across the Rdson of the low side MOSFET. Current limit

point is this voltage divided by the Rds-on. Once this threshold is reached the

Hdrv and Ldrv pins are switched low and an internal hiccup circuit is set that

recycles the soft start circuit after 2048 switching cycles.

Thesepi

nsareconnectedtosourceofhi

ghsi

deFETsandprovi

dereturnpathfor

thehi

ghsi

dedrivers.Theyareal

sousedtohol

dthel

ow si

dedriversl

ow untilt

his

pi

ni

sbroughtl

ow bytheacti

onofhi

ghsi

deturni

ngoff.LDRVscanonl

ygohi

ghif

SW i

sbel

ow 1V threshol

d .

Hi

ghsi

degatedriveroutputs.

Thi

spi

nsuppli

esvolt

agetohi

ghsi

deFET driver.Ahi

ghfreq1uFceram i

ccapaci-

torispl

acedascl

oseaspossi

bl

e toandconnected tothesepi

nsandrespected

SW pi

ns.

Suppl

yvolt

ageforthel

ow si

defetdrivers.Ahi

ghfrequency1uFceram i

ccapm ust

beconnectedfrom thi

spi

ntothePGND1andPGND2pi

nascl

oseaspossi

bl

eto

the pi

ns.

Low si

degatedriveroutputs.

Powergroundpi

nforlow si

dedrivers.

Thi

spi

ni

sthefirsterroram pli

fiernon-inverti

ngi

nput.Thi

spi

nshoul

dbecon-

nectedeit

hertoanexternalreferencevolt

age(tracki

ngappli

cati

on)ortothe

i

nternalreferencevolt

ageprovi

dedbythi

sdevi

ce.

Referencevolt

ageavail

abl

e.A100pFcapacit

orcanbeconnectedfrom thi

spi

nto

GND.Thi

spi

ni

shel

dl

ow untili

nternalVccUVLO andtheENSW 1pi

naregood,

all

owi

ng itto softstart.

14

27

15

26

16

25

17

24

18

23

19

22

20

21

30

31

32

OCP2

OCP1

SW2

SW1

HDRV2

HDRV1

BST2

BST1

PVCC2

PVCC1

LDRV2

LDRV1

PGND2

PGND1

VP

VREF

NC