LTC3528B datasheet(11/16 Pages) LINER

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LTC3528/LTC3528B

3528fa

APPLICATIONS INFORMATION

The inductor current ripple is typically set for 20% to

40% of the maximum inductor current. High frequency

ferrite core inductor materials reduce frequency depen-

dent power losses compared to cheaper powdered iron

types, improving efﬁciency. The inductor should have low

ESR (series resistance of the windings) to reduce the I2R

power losses, and must be able to handle the peak induc-

tor current without saturating. Molded chokes and some

chip inductors usually do not have enough core area to

support the peak inductor currents of 1.5A seen on the

LTC3528/LTC3528B. To minimize radiated noise, use a

shielded inductor. See Table 1 for suggested components

and suppliers.

Table 1. Recommended Inductors

VENDOR

PART/STYLE

Coilcraft

(847) 639-6400

www.coilcraft.com

LPO2506, MSS5131

MSS6122, MOS6020

ME3220, DO1608C

1812PS

Coiltronics

SD14, SD18, SD20

SD25, SD52

Sumida

(847) 956-0666

www.sumida.com

CD43

CDC5D23B

CDRH5D18

CR43

TDK

VLP, VLF

VLCF, SLF

Toko

(408) 432-8282

www.tokoam.com

D53, D63

D73, D75

Wurth

(201) 785-8800

www.we-online.com

WE-TPC type M, MH

Output and Input Capacitor Selection

Low ESR (equivalent series resistance) capacitors should

be used to minimize the output voltage ripple. Multilayer

ceramic capacitors are an excellent choice as they have

extremely low ESR and are available in small footprints.

A 10μF to 22μF output capacitor is sufﬁcient for most ap-

plications. Values larger than 22μF may be used to obtain

extremely low output voltage ripple and improve transient

response. X5R and X7R dielectric materials are preferred

for their ability to maintain capacitance over wide voltage

and temperature ranges. Y5V types should not be used.

The internal loop compensation of the LTC3528/LTC3528B

is designed to be stable with output capacitor values of 10μF

or greater. Although ceramic capacitors are recommended,

low ESR tantalum capacitors may be used as well.

A small ceramic capacitor in parallel with a larger tantalum

capacitor may be used in demanding applications which

have large load transients. Another method of improving

the transient response is to add a small feed-forward

capacitor across the top resistor of the feedback divider

(from VOUT to FB). A typical value of 33pF will generally

sufﬁce.

Low ESR input capacitors reduce input switching noise

and reduce the peak current drawn from the battery. It

follows that ceramic capacitors are also a good choice

for input decoupling and should be located as close as

possible to the device. A 10μF input capacitor is sufﬁcient

for most applications. Larger values may be used without

limitations. Table 2 shows a list of several ceramic capaci-

tor manufacturers. Consult the manufacturers directly for

detailed information on their selection of ceramic parts.

Table 2. Capacitor Vendor Information

SUPPLIER

PHONE

WEBSITE

AVX

(803) 448-9411

www.avxcorp.com

Murata

(714) 852-2001

www.murata.com

Taiyo-Yuden

(408) 573-4150

www.t-yuden.com

TDK

(847) 803-6100

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