LTC3539_15 Datasheet, PDF (10/14 Pages) Linear Technology – 2A, 1MHz/2MHz Synchronous Step-Up DC/DC Converters

LTC3539/LTC3539-2
APPLICATIONS INFORMATION
Table 1. Representative Inductors
VENDOR
PART/STYLE
Coilcraft
[phone]
www.coilcraft.com
MSS5131
LPS4018-222
MSS6132
MOS6020
Murata
www.murata.com
LQH55D
LQH66S
Sumida
[phone]
www.sumida.com
CDRH4D22
CDRH4D28C
CDRH5D28
CDR6D23
TDK
[phone]
www.component.tdk.com
VLF5014ST
Toko
[phone]
www.tokoam.com
D53LC
D63LCB
Würth
[phone]
www.we-online.com
WE-TPC Type LH, X
WE-PD Type XS
Output and Input Capacitor Selection
The internal loop compensation of the LTC3539 is designed
to be stable with output capacitor values of 22µF or greater.
Although ceramic capacitors are recommended, low ESR
(equivalent series resistance) tantalum capacitors may be
used as well.
Low ESR 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 22µF to 47µF output
capacitor is sufficient for output voltages of 3V or greater.
An output capacitor of up to 100µF is required at lower
output voltages. Even with V_OUT greater than 3V, larger
values up to 100µF 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.
A small ceramic capacitor in parallel with a larger tantalum
capacitor may be used in demanding applications which
have large load transients. A feedforward capacitor across
the top resistor of the feedback divider (from V_OUT to FB)
is usually required to improve transient response. 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 2.2µF 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
[phone]
www.avxcorp.com
Murata
[phone]
www.murata.com
Taiyo-Yuden [phone]
www.t-yuden.com
TDK
[phone]
www.component.tdk.com
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For more information www.linear.com/3539/3539-2
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