LT1618EDD Linear Technology, LT1618EDD Datasheet - Page 6

• Manufacturer Part Number: LT1618EDD
• Description: IC CONV DC/DC STEPUP CC/CV 10DFN
• Manufacturer: Linear Technology
• Type: Step-Up (Boost)r

Specifications of LT1618EDD

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 1.26 ~ 36 V
• Current - Output: 1.5A
• Frequency - Switching: 1.4MHz
• Voltage - Input: 1.6 ~ 18 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 10-DFN
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -

LT1618
Capacitor Selection
Low ESR (equivalent series resistance) capacitors should
be used at the output to minimize the output ripple voltage.
Multilayer ceramic capacitors are an excellent choice.
They have an extremely low ESR and are available in very
small packages. X5R and X7R dielectrics are preferred, as
these materials retain their capacitance over wider voltage
and temperature ranges than other dielectrics. A 4.7µF to
10µF output capacitor is sufficient for high output current
designs. Converters with lower output currents may need
only a 1µF or 2.2µF output capacitor. Solid tantalum or
OSCON capacitors can be used, but they will occupy more
board area than a ceramic and will have a higher ESR for
6
APPLICATIONS
Inductor Selection
Several inductors that work well with the LT1618 are listed
in Table 1, although there are many other manufacturers
and devices that can be used. Consult each manufacturer
for more detailed information and for their entire selection
of related parts. Many different sizes and shapes are
available. Ferrite core inductors should be used to obtain
the best efficiency, as core losses at 1.4MHz are much
lower for ferrite cores than for the cheaper powdered-iron
ones. Choose an inductor that can handle the necessary
peak current without saturating, and ensure that the
inductor has a low DCR (copper-wire resistance) to mini-
mize I
a good choice for many LT1618 designs.
Table 1. Recommended Inductors
PART
CDRH5D18-4R1
CDRH5D18-100
CR43-2R2
CR43-4R7
CR43-100
CR54-100
LQH3C1R0M24
LQH3C2R2M24
LQH3C4R7M24
2
R power losses. A 4.7µH or 10µH inductor will be
(µH)
4.1
2.2
4.7
1.0
2.2
4.7
10
10
10
L
U
(mΩ)
MAX
124
109
182
100
126
260
INFORMATION
57
71
78
U
HEIGHT
(mm)
2.0
2.0
3.5
3.5
3.5
4.8
2.0
2.0
2.0
W
VENDOR
Sumida
[phone]
www.sumida.com
Murata
[phone]
www.murata.com
U
the same footprint device. Always use a capacitor with a
sufficient voltage rating.
Ceramic capacitors also make a good choice for the input
decoupling capacitor, which should be placed as close as
possible to the V
capacitor is sufficient for most applications. Table 2 shows
a list of several ceramic capacitor manufacturers. Consult
the manufacturers for detailed information on their entire
selection of ceramic parts.
Table 2. Recommended Ceramic Capacitor Manufacturers
VENDOR
Taiyo Yuden
Murata
Kemet
Diode Selection
Schottky diodes, with their low forward voltage drop and
fast switching speed, are the ideal choice for LT1618
applications. Table 3 shows several Schottky diodes that
work well with the LT1618. Many different manufacturers
make equivalent parts, but make sure that the component
chosen has a sufficient current rating and a voltage rating
greater than the output voltage. The diode conducts cur-
rent only when the power switch is turned off (typically
less than half the time), so a 0.5A or 1A diode will be
sufficient for most designs. The companies below also
offer Schottky diodes with higher voltage and current
ratings.
Table 3. Recommended Schottky Diodes
1A PART
UPS120
UPS130
UPS140
MBRM120 MBR0520
MBRM130 MBR0530
MBRM140 MBR0540
B120
B130
B140
0.5A PART
B0520
B0530
B0540
PHONE
[phone]
[phone]
[phone]
IN
pin of the LT1618. A 1µF to 4.7µF input
VENDOR
Microsemi
ON Semiconductor [phone]
Diodes, Inc
URL
www.t-yuden.com
www.murata.com
www.kemet.com
PHONE/URL
[phone]
www.microsemi.com
www.onsemi.com
[phone]
www.diodes.com
sn1618 1618fas