LTC3455EUF#TRPBF Linear Technology, LTC3455EUF#TRPBF Datasheet - Page 17

• Manufacturer Part Number: LTC3455EUF#TRPBF
• Description: IC CONV DC/DC DUAL USBBATT 24QFN
• Manufacturer: Linear Technology

Specifications of LTC3455EUF#TRPBF

• Applications: Handheld/Mobile Devices
• Voltage - Supply: 3 V ~ 6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Supply: -

APPLICATIONS INFORMATION
Switching Regulator Inductor Selection
Many different sizes and shapes of inductors are avail-
able from numerous manufacturers. Choosing the right
inductor from such a large selection of devices can be
overwhelming, but following a few basic guidelines will
make the selection process much simpler. To maximize
effi ciency, choose an inductor with a low DC resistance.
Keep in mind that most inductors that are very thin or have
a very small volume typically have much higher core and
DCR losses, and will not give the best effi ciency.
Choose an inductor with a DC current rating at least 1.5
times larger than the maximum load current to ensure that
the inductor does not saturate during normal operation.
Table 1 shows several inductors that work well with the
LTC3455/LTC3455-1. These inductors offer a good com-
promise in current rating, DCR and physical size. Consult
each manufacturer for detailed information on their entire
selection of inductors.
Table 1. Recommended Inductors
CDRH3D16
CLS4D09
Inductor
DB318C
ELT5KT
SD12
Type
(μH)
4.7
4.7
4.7
4.7
4.7
10
10
10
10
10
L
Max
0.86
0.58
0.75
0.55
1.29
0.82
0.68
IDC
(A)
0.5
0.9
1
Max
DCR
0.18
0.19
0.37
0.11
0.21
0.12
0.28
0.36
(Ω)
0.1
0.2
Height
(mm)
1.8
1.8
1.8
1.8
1.2
1.2
1.2
1.2
1
1
www.panasonic.com
www.cooperet.com
www.sumida.com
[phone]
www.toko.com
[phone]
[phone]
[phone]
Manufacturer
Panasonic
Sumida
Sumida
Cooper
Toko
Switching Regulator Output Capacitor Selection
Low ESR (equivalent series resistance) ceramic capacitors
should be used at both switching regulator outputs. Only
X5R or X7R ceramic capacitors should be used because
they retain their capacitance over wider voltage and tem-
perature ranges than other ceramic types. A 10μF output
capacitor is suffi cient for most applications. Table 2 shows
a list of several ceramic capacitor manufacturers. Consult
each manufacturer for detailed information on their entire
selection of ceramic capacitors. Many manufacturers now
offer very thin (<1mm tall) ceramic capacitors ideal for
use in height-restricted designs.
Table 2. Recommended Ceramic Capacitor Manufacturers
Taiyo Yuden
AVX
Murata
TDK
V
For the V
best choice. Only X5R or X7R type ceramic capacitors
should be used.
V
For the V
choice. Only X5R or X7R type ceramic capacitors should
be used. Do not use less than 10μF on this pin. For some
designs it may be desirable to use a larger capacitor con-
nected to V
LTC3455-1 are USB powered. Up to 50μF of ceramic
capacitance may be connected to the V
diffi culty. More than 50μF requires using a capacitor with
some ESR (like a Tantalum or OS-CON) or adding some
resistance in series with some of the ceramic capacitance.
This is necessary to ensure loop stability in the battery
charger loop when under USB power.
BAT
MAX
Pin Capacitor Selection
Pin Capacitor Selection
BAT
MAX
MAX
pin, a 4.7μF to 10μF ceramic capacitor is the
pin, a 10μF ceramic capacitor is the best
to act as a reservoir when the LTC3455/
LTC3455/LTC3455-1
[phone]
[phone]
[phone]
[phone]
www.avxcorp.com
www.t-yuden.com
www.murata.com
MAX
www.tdk.com
pin without
17
3455fc