LTC3535 Datasheet, PDF (13/16 Pages) Linear Technology – Dual Channel 550mA 1MHz Synchronous Step-Up DC/DC Converter

LTC3535
APPLICATIONS INFORMATION
Table 1. Recommended Inductors
VENDOR
PART/STYLE
Coilcraft
[phone]
www.coilcraft.com
LPO4815
LPS4012, LPS4018
MSS5131
MSS4020
MOS6020
ME3220
DS1605, DO1608
Coiltronics
www.cooperet.com
SD10, SD12, SD14, SD18, SD20,
SD52, SD3114, SD3118
FDK
[phone]
www.fdk.com
MIP3226D4R7M, MIP3226D3R3M
MIPF2520D4R7
MIPWT3226D3R0
Murata
[phone]
www.murata.com
LQH43C
LQH32C (-53 series)
301015
Sumida
[phone]
www.sumida.com
CDRH5D18
CDRH2D14
CDRH3D16
CDRH3D11
CR43
CMD4D06-4R7MC
CMD4D06-3R3MC
Taiyo-Yuden
www.t-yuden.com
NP03SB
NR3015T
NR3012T
TDK
[phone]
www.component.tdk.com
VLP
VLF, VLCF
Toko
[phone]
www.tokoam.com
D412C
D518LC
D52LC
D62LCB
Wurth
[phone]
www.we-online.com
WE-TPC type S, M
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
4.7μF to 10μF output capacitor is sufficient for most ap-
plications. Larger values 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 LTC3535 is designed
to be stable with output capacitor values of 4.7μF or greater
(without the need for any external series resistor). 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 that 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 V_OUT
to FB). A typical value of 22pF 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, although larger values may be
used without limitations. Table 2 shows a list of several
ceramic capacitor manufacturers. Consult the manufactur-
ers directly for detailed information on their selection of
ceramic capacitors.
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
Samsung
[phone]
www.sem.samsung.com
3535f
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