LTC3559 Linear Technology, LTC3559 Datasheet - Page 21

• Manufacturer Part Number: LTC3559
• Description: Linear USB Battery Charger
• Manufacturer: Linear Technology

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APPLICATIONS INFORMATION
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.
Table 2 Recommended Inductors
*Typical DCR
INDUCTOR TYPE
CDRH3D16
CDRH2D11
DE2812C
CLS4D09
LPS3015
DB318C
SD3118
SD3112
D312C
SD12
SD10
L (μH)
4.7
3.3
4.7
3.3
4.7
3.3
4.7
3.3
4.7
3.3
4.7
4.7
3.3
4.7
3.3
4.7
3.3
4.7
3.3
4.7
3.3
MAX I
1.07
1.20
0.79
0.90
1.15
1.37
0.75
1.59
0.97
1.29
1.42
1.08
1.31
0.9
1.1
0.5
0.6
1.3
0.8
1.1
1.3
DC
(A)
MAX DCR(Ω)
0.105*
0.117*
0.104*
0.153*
0.108*
0.13*
0.085
0.123
0.162
0.113
0.246
0.165
0.07
0.24
0.20
0.11
0.17
0.19
0.13
0.1
0.2
Table 3: Recommended Ceramic Capacitor Manufacturers
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
and output capacitors must all be placed as close to the
LTC3559 as possible and on the same side as the LTC3559.
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.
The Exposed Pad must also be soldered to system ground
for proper operation.
Taiyo Yuden
Murata
AVX
TDK
SIZE IN MM (L × W × H)
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
3.2 × 3.2 × 1.2
3.2 × 3.2 × 1.2
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
3.0 × 3.0 × 1.5
3.0 × 3.0 × 1.5
4.9 × 4.9 × 1
4 × 4 × 1.8
4 × 4 × 1.8
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www.cooperet.com
www.coilcraft.com
www.sumida.com
MANUFACTURER
www.toko.com
LTC3559
www.avxcorp.com
www.t-yuden.com
www.murata.com
Coilcraft
Sumida
Cooper
www.tdk.com
Toko
IN
capacitor
21
3559f