LTC3450EUD#PBF Linear Technology, LTC3450EUD#PBF Datasheet - Page 9

• Manufacturer Part Number: LTC3450EUD#PBF
• Description: IC CONV PS TRIPLE TFT/LCD 16QFN
• Manufacturer: Linear Technology

Specifications of LTC3450EUD#PBF

• Applications: Converter, TFT, LCD
• Voltage - Input: 1.5 ~ 4.6 V
• Number Of Outputs: 3
• Voltage - Output: 5.1V, -5V, ±10V, ±15V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-WQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIO S I FOR ATIO
Inductor Selection
Inductors in the range of 47µH to 100µH with saturation
current (I
for use with the LTC3450. Ferrite core materials are
strongly recommended for their superior high frequency
performance characteristics. A bobbin or toroid type core
will reduce radiated noise. Inductors meeting these re-
quirements are listed in Table 1.
Table 1. Recommended Inductors
PART
NUMBER
CLQ4D10-470
CLQ4D10-101
CMD4D08-470
DO1606-473
DO1606-104
DT1608-473
DT1608-104
LQH43MN470J03 47
LQH43MN101J03 100
DU6629-470M
DU6629-101M
Capacitor Selection
The boost converter requires two capacitors. The input
capacitor should be an X5R type of at least 1µF. The V
capacitor should also be an X5R type between 2.2µF and
10µF. A larger capacitor (10µF) should be used if lower
output ripple is desired or the output load required is close
to the 10mA maximum.
The charge pumps require flying capacitors of at least
0.1µF to obtain specified performance. Ceramic X5R types
are strongly recommended for their low ESR and ESL and
capacitance versus bias voltage stability. The filter capaci-
tor on V2X should be at least 0.1µF. A 0.47µF or larger
capacitor on V2X is recommended if V
V2X. The filter capacitors on V3X and V
0.1µF or larger. Please be certain that the capacitors used
are rated for the maximum voltage with adequate safety
margin. Refer to Table 2 for a listing of capacitor vendors.
Table 2. Capacitor Vendor Information
Supplier
AVX
Murata
Taiyo Yuden
SAT
) ratings of at least 150mA are recommended
(µH)
100
100
100
100
47
47
47
47
47
L
MAX DCR HEIGHT
U
Phone
[phone]
[phone]
[phone]
1.28
3.15
0.34
0.64
1.27
(Ω)
1.6
1.1
2.3
1.1
2.5
1.5
U
(mm) VENDOR
2.92
2.92
1.2
1.0
2.0
2.6
Sumida
[phone]
www.sumida.com
Coilcraft
[phone]
www.coilcraft.com
Murata
www.murata.com
Coev Magnetics
www.circuitprotection.com
W
INV
Website
www.avxcorp.com
www.murata.com
www.t-yuden.com
is connected to
NEG
should be
U
OUT
Soft-Start
Soft-start operation provides a gradual increase in the
current drawn from the input power source (usually a
battery) during initial startup of the LTC3450, eliminating
the inrush current which is typical in most boost convert-
ers. This reduces stress on the input power source, boost
inductor and output capacitor, reduces voltage sag on the
battery and increases battery life. The rate at which the
input current will increase is set by two external compo-
nents (R
2). Upon initial application of power or release of a pull
down switch on SHDN, the voltage on SHDN will increase
relative to the R • C time constant or R
time constant SHDN will rise to approximately 63.2% of
the voltage on V
SHDN, no switching will occur because the shutdown
threshold is 0.77V (typ). From 0.77V to 1V the maximum
switch pin current capability of the LTC3450 will gradually
increase from near zero to the maximum current limit. An
R
SHDN is driven high with a logic signal, the input current
will gradually increase to its maximum value in approxi-
mately 50µs.
Printed Circuit Board Layout Guidelines
High speed operation of the LTC3450 demands careful
attention to PCB layout. You will not get advertised perfor-
mance with careless layout. Figure 3 shows the recom-
mended component placement for a single layer PCB. A
multilayer board with a separate ground plane is ideal but
not absolutely necessary.
SS
in the range of 1MΩ to 10MΩ is recommended. If
SS
Figure 2. Soft-Start Component Configuration
and C
IN
SS
1ms SOFT-START WITH 3.6V V
. From 0V to approximately 0.77V on
) connected to SHDN (refer to Figure
V
IN
R
1M
5%
SS
C
6.8nF
SS
5 SHDN
3450 F02
IN
SS
LTC3450
• C
SS
. After one
3450fa
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