LTC3534 Linear Dimensions Semiconductor, LTC3534 Datasheet - Page 12

• Manufacturer Part Number: LTC3534
• Description: 500mA Synchronous Buck-Boost DC
• Manufacturer: Linear Dimensions Semiconductor

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LTC3534
APPLICATIONS INFORMATION
COMPONENT SELECTION
Inductor Selection
The high frequency operation of the LTC3534 allows the
use of small surface mount inductors. The inductor ripple
current is typically set to 20% to 40% of the maximum
inductor current. For a given ripple the inductance terms
are given as follows:
where f = switching frequency in Hz, typically 1MHz.
12
L
L
BOOST
BUCK
Figure 4. Recommended Component Placement. Traces Carrying High Current are Direct. Trace Area at FB and V
Kept Low. Lead Length to Battery Should be Kept Short. Keep V
>
>
V
V
OUT
IN(MIN)
f • ΔI
• V
(
f • ΔI
L
IN(MAX)
• V
Table 1. Inductor Vendor Information
SUPPLIER
Coilcraft
FDK
Murata
Sumida
TDK
TOKO
(
• V
L
OUT
IN(MAX)
• V
– V
– V
OUT
OUT
IN(MIN)
PHONE
[phone]
[phone]
[phone]
[phone]
USA: [phone]
Japan: 81(3) 3607-5111
[phone]
[phone]
)
H
)
2
3
4
5
6
7
H
RUN/SS
GND
PGND1
SW1
SW2
PGND2
PWM
FAX OR E-MAIL
[phone]
[e-mail]
[phone]
USA: [phone]
Japan: 81(3) 3607-5144
[phone]
[phone]
V
PV
OUT
V
FB
V
IN
IN
C
MULTIPLE VIAS
15
14
13
12
11
10
ΔI
V
V
V
For high effi ciency, choose a ferrite inductor with a high
frequency core material to reduce core loses. The induc-
tor should have low ESR (equivalent series resistance) to
reduce the I
inductor current without saturating. Molded chokes or chip
inductors usually do not have enough core to support the
peak inductor currents in the 1A to 2A region. To minimize
radiated noise, use a shielded inductor. See Table 1 for a
suggested list of inductor suppliers.
IN(MIN)
IN(MAX)
OUT
OUT
L
= maximum allowable inductor ripple current, A
and V
= output voltage, V
= minimum input voltage, V
= maximum input voltage, V
IN
2
Ceramic Capacitors Close to their IC Pins.
R losses, and must be able to handle the peak
3534 F04
WEBSITE
www.coilcraft.com
www.fdk.com
www.murata.com
www.sumida.com
www.component.tdk.com
www.tokoam.com
V
V
PWM
IN
OUT
C
Pins are
3534f