Datasheet

LTC3559/LTC3559-1
21
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Table 2 Recommended Inductors
INDUCTOR TYPE L (μH) MAX I
DC
(A)
MAX DCR(Ω) SIZE IN MM (L × W × H)
MANUFACTURER
DB318C
D312C
DE2812C
4.7
3.3
4.7
3.3
4.7
3.3
1.07
1.20
0.79
0.90
1.15
1.37
0.1
0.07
0.24
0.20
0.13*
0.105*
3.8 × 3.8 × 1.8
3.8 × 3.8 × 1.8
3.6 × 3.6 × 1.2
3.6 × 3.6 × 1.2
3.0 × 2.8 × 1.2
3.0 × 2.8 × 1.2
Toko
www.toko.com
CDRH3D16
CDRH2D11
CLS4D09
4.7
3.3
4.7
3.3
4.7
0.9
1.1
0.5
0.6
0.75
0.11
0.085
0.17
0.123
0.19
4 × 4 × 1.8
4 × 4 × 1.8
3.2 × 3.2 × 1.2
3.2 × 3.2 × 1.2
4.9 × 4.9 × 1
Sumida
www.sumida.com
SD3118
SD3112
SD12
SD10
4.7
3.3
4.7
3.3
4.7
3.3
4.7
3.3
1.3
1.59
0.8
0.97
1.29
1.42
1.08
1.31
0.162
0.113
0.246
0.165
0.117*
0.104*
0.153*
0.108*
3.1 × 3.1 × 1.8
3.1 × 3.1 × 1.8
3.1 × 3.1 × 1.2
3.1 × 3.1 × 1.2
5.2 × 5.2 × 1.2
5.2 × 5.2 × 1.2
5.2 × 5.2 × 1.0
5.2 × 5.2 × 1.0
Cooper
www.cooperet.com
LPS3015 4.7
3.3
1.1
1.3
0.2
0.13
3.0 × 3.0 × 1.5
3.0 × 3.0 × 1.5
Coilcraft
www.coilcraft.com
*Typical DCR
Buck Switching Regulator
Input/Output Capacitor Selection
Low ESR (equivalent series resistance) ceramic capaci-
tors should be used at both switching regulator outputs
as well as the switching regulator input supply. Only
X5R or X7R ceramic capacitors should be used because
they retain their capacitance over wider voltage and
temperature ranges than other ceramic types. A 10μF
output capacitor is suffi cient for most applications.
For good transient response and stability the output
capacitor should retain at least 4μF of capacitance over
operating temperature and bias voltage. The switching
regulator input supply should be bypassed with a 2.2μF
capacitor. Consult manufacturer for detailed information
on their selection and specifi cations of ceramic capaci-
tors. Many manufacturers now offer very thin (< 1mm
tall) ceramic capacitors ideal for use in height-restricted
designs. Table 3 shows a list of several ceramic capacitor
manufacturers.
APPLICATIONS INFORMATION
Table 3: Recommended Ceramic Capacitor Manufacturers
AVX [phone] www.avxcorp.com
Murata [phone] www.murata.com
Taiyo Yuden [phone] www.t-yuden.com
TDK [phone] www.tdk.com
PCB Layout Considerations
As with all DC/DC regulators, careful attention must be
paid while laying out a printed circuit board (PCB) and to
component placement. The inductors, input PV
IN
capacitor
and output capacitors must all be placed as close to the
LTC3559/LTC3559-1 as possible and on the same side as
the LTC3559/LTC3559-1. All connections must be made on
that same layer. Place a local unbroken ground plane below
these components that is tied to the Exposed Pad (Pin 17)
of the LTC3559/LTC3559-1. The Exposed Pad must also
be soldered to system ground for proper operation.