LTC3528B-2 데이터 시트보기 (PDF) - Linear Technology

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LTC3528B-2

1A, 2MHz Synchronous Step-Up DC/DC Converter in 2mm × 3mm DFN

Linear Technology 

LTC3528B-2

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 dependent

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 inductor current

without saturating. Molded chokes and some chip induc-

tors usually do not have enough core area to support the

peak inductor currents of 1.5A seen on the LTC3528B-2.

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

DO1606T, MSS5131, MSS5121

MSS6122, MOS6020

ME3220, DO1608C

1812PS

Coiltronics

SD12, SD14, SD20

SD25, SD52

Sumida

(847) 956-0666

www.sumida.com

CD43

CDC5D23B

CDRH5D18

TDK

VLP, VLF

VLCF, SLF, VLS

Toko

(408) 432-8282

www.tokoam.com

D53, D62, 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 LTC3528B-2 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 capaci-

tor 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 www.component.tdk.com

3528b2fa

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