ZXLD1371QESTTC datasheet(25/42 Pages) DIODES

25 / 42 page

ZXLD1371

Document number

Applicatio

Buck topolo

In Buck mod

current depe

above,

If ADJ is dire

Boost and B

For Boost a

upon the re

above. The

there is not a

If ADJ is con

GI_ADJ is g

Note that from

22k

Ω

The additiona

As mentioned

Buck-boost c

0.2 <

The mean vo

VRS =

Note that if G

same coil cu

consider Equ

This shows th

example if D

increase the

offset uncerta

100mV.

r: DS35436 Rev. 1

ons Inform

ogy

de, GI is conn

ends only upo

ectly connected

Buck-boost to

and Buck-boos

esistors, RS, R

ere is more than

a unique soluti

nnected to REF

iven by Equati

m consideration

Ω < RGI1 < 10

al degree of fre

d above, the w

onfiguration is

< GI_ADJ < 0

ltage across th

= ICOIL RS

GI_ADJ is made

urrent, the diss

uation 5. If AD

hat VRS becom

= 0.2, and GI

LED current e

ainty in the ZX

- 2

mation (cont

nected to ADJ

n RS, VADJ and

d to VREF, this

opology

st topologies,

RGI1, and RGI2

n one degree o

on. From Equ

F, this becomes

ion 2, repeated

ns of ZXLD137

Ω

eedom allows

working voltage

0.5

he sense resist

e larger, these

sipation in RS

DJ is connected

mes smaller tha

_ADJ is the m

rror due to sm

XLD1371. If no

t.)

as in Figure 5

d VREF. From

s becomes:

the LED curre

as in Equatio

of freedom. Th

uation 4,

d here for conv

71 input bias cu

us to select G

e range at the

or is

equations sho

is increased.

d to REF, this b

an 225mV if GI

minimum value

all offsets in th

ow, GI_ADJ is

25 of 42

ww.diodes.com

5. The LED

Equation 1

quation 10

ent depends

ons 4 and 2

hat is to say,

quation 11

venience:

urrent, the reco

I_ADJ within li

GI pin is rest

ow that RS is in

So, in some

becomes

I_ADJ < 1 - D.

of 0.2, then V

he system, suc

increased to

Dio

Figure

Figure 6.

ommended limi

imits but this m

ricted. The pe

ncreased and V

cases, it is be

. If also D is s

VRS becomes 0

ch as mV drop

0.4 or 0.5, VRS

A Product Lin

odes Incorpor

e 5. Setting LE

configu

Setting LED

Buck-boost co

ts for RGI1 are:

may affect over

ermitted range

VRS

is increas

etter to minimi

small, VRS can

.225* 0.2 / 0.8

in the copper

S is increased

Febru

ne of

rated

ED current in B

ration

current in Boo

onfigurations

Equation 12

rall performanc

of GI_ADJ in

Equation 13

Equation 14

sed. Therefor

ize GI_ADJ.

become too sm

8 = 56.25 mV.

printed wiring

to a value gre

LD1371

uary 2012

Incorporated

Buck

ost and

ce a little.

Boost or

re, for the

However,

mall. For

This will

circuit, or

eater than

ZXLD1371QESTTC Datasheet(PDF) 25 Page - Diodes Incorporated

ZXLD1371QESTTC Datasheet(HTML) 25 Page - Diodes Incorporated

Html Pages

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 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42

Datasheet Download

Link URL