LTC3459 LINER [Linear Technology], LTC3459 Datasheet - Page 8

• Manufacturer Part Number: LTC3459
• Description: 10V Micropower Synchronous Boost Converter in ThinSOT
• Manufacturer: LINER [Linear Technology]

OPERATIO
APPLICATIO S I FOR ATIO
LTC3459
overshoot. The t
tively constant peak-to-peak current in the inductor de-
spite V
period by approximately 1/(V
tion delays and a 0.6 A bias current in the timer, the t
time can be more accurately predicted as follows:
Inductor Selection
An inductor with a minimum value of 15 H is recom-
mended for use with the LTC3459. Values larger than
15 H will result in lower ripple current and switching
frequency. High frequency Ferrite core materials are
strongly recommended. Some inductors meeting these
requirements are listed in Table 2.
Table 2. Example Inductors
VENDOR/PART
Chip Inductors
Murata
LQH31C
LQH32C-Low Profile 22
Taiyo Yuden
LB2016
Toko
LLB2520
Coilcraft
DO3314
DO1606T
Sumida
CMD4D06
CDRJ2D18LD
Capacitor Selection
The boost converter requires two capacitors. The input
capacitor should be an X5R type of at least 1.0 F. The V
8
IN
changes. This is accomplished by varying the t
OFF
( H) I
22
15
22
33
15
22
33
15 0.86/650 3.3 3.3 1.4 [phone]
22
15
22
33 0.74/450
15
22
33
15 0.175/350 3.2 3.2 2.0
22 0.255/300
33 0.37/240
U
L
U
timer is designed to maintain a rela-
DCR ( )/ DIMENSIONS
MAX
0.7/250
0.7/130
1.7/180
2.5/160
3.8/130
1.2/500
0.4/700
0.5/500
0.5/400
0.8/300
1.3/240
1.7/85
3/160
1/105
(mA)
U
OUT
3.2 1.6 1.8
3.2 2.5 1.6
2.0 1.6 1.6 [phone]
2.5 2.0 1.6 [phone]
6.5 5.3 2.0
6.6 5.8 0.8 [phone]
– V
(mm)
W
IN
). Due to propaga-
www.coilcraft.com
www.t-yuden.com
www.tokoam.com
www.sumida.com
www.murata.com
INFORMATION
CONTACT
U
OUT
OFF
OFF
If V
mately 750ns.
capacitor should also be an X5R type between 2.2 F and
10 F. A larger capacitor should be used if lower peak-to-
peak output ripple and better line regulation is desired.
Table 2. Capacitor Vendor Information
SUPPLIER
AVX
Murata
Taiyo Yuden
TDK
PCB Layout Guidlines
The high speed operation of the LTC3459 demands careful
attention to board layout. You will not get advertised
performance with careless layout. Figure 4 shows the
recommended component placement. A large ground pin
copper area will help to lower the chip temperature.
t
OUT
OFF
is less than V
RECOMMENDED COMPONENT PLACEMENT. TRACES
CARRYING CURRENT ARE DIRECT. TRACE AREA AT FB
PIN IS SMALL. LEAD LENGTH TO BATTERY IS SHORT
V
100
IN
Figure 4. Recommended Component
Placement for Single Layer Board
ns
PHONE
[phone]
[phone]
[phone]
[phone]
0 6
.
IN
0 8
, the t
.
A
pF
1
2
3
V
OFF
• .
SW
GND
FB
OUT
1 25
500
delay is fixed at approxi-
SHDN
3459 F04
V
OUT
–
V
V
IN
k
WEBSITE
www.avxcorp.com
www.murata.com
www.t-yuden.com
www.component.tdk.com
V
V
IN
OUT
6
5
4
SHDN
3459f