LTC3559-1_15 Datasheet, PDF (21/24 Pages) Linear Technology – Linear USB Battery Charger with Dual Buck Regulators

LTC3559/LTC3559-1
APPLICATIONS INFORMATION
Table 2 Recommended Inductors
INDUCTOR TYPE
L (μH)
DB318C
4.7
3.3
D312C
4.7
3.3
DE2812C
4.7
3.3
CDRH3D16
4.7
3.3
CDRH2D11
4.7
3.3
CLS4D09
4.7
SD3118
4.7
3.3
SD3112
4.7
3.3
SD12
4.7
3.3
SD10
4.7
3.3
LPS3015
4.7
3.3
*Typical DCR
MAX I_DC(A)
1.07
1.20
0.79
0.90
1.15
1.37
0.9
1.1
0.5
0.6
0.75
1.3
1.59
0.8
0.97
1.29
1.42
1.08
1.31
1.1
1.3
MAX DCR(Ω)
0.1
0.07
0.24
0.20
0.13*
0.105*
0.11
0.085
0.17
0.123
0.19
0.162
0.113
0.246
0.165
0.117*
0.104*
0.153*
0.108*
0.2
0.13
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
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
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
MANUFACTURER
Toko
www.toko.com
Sumida
www.sumida.com
Cooper
www.cooperet.com
Coilcraft
www.coilcraft.com
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 sufficient 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 specifications 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 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.
3559fb
21