lt3466efe-trpbf Linear Technology Corporation, lt3466efe-trpbf Datasheet - Page 11

• Manufacturer Part Number: lt3466efe-trpbf
• Description: White Led Driver And Boost Converter In 3mm X 3mm Dfn Package
• Manufacturer: Linear Technology Corporation

APPLICATIO S I FOR ATIO
The inductor current ripple (∆I
across the Schottky diode and the switch, is given by :
where:
The ∆I
inductor current.
The inductor should have a saturation current rating
greater than the peak inductor current required for the
application. Also, ensure that the inductor has a low DCR
(copper wire resistance) to minimize I
Recommended inductor values range from 10µH to 68µH.
Several inductors that work well with the LT3466-1 are listed
in Table 1. Consult each manufacturer for more detailed
information and for their entire selection of related parts.
Table 1. Recommended Inductors
PART
LQH32CN100
LQH32CN150
LQH43CN330
ELL6RH330M
ELL6SH680M
A914BYW330M
A914BYW470M
A920CY680M
CDRH2D18150NC
CDRH4D18-330
CDRH5D18-680
CAPACITOR SELECTION
The small size of ceramic capacitors make them ideal for
LT3466-1 applications. Use only X5R and X7R types
because they retain their capacitance over wider voltage
and temperature ranges than other types such as Y5V or
L = Inductor
f = Operating frequency
V
V
∆ =
IN(MIN)
OUT(MAX)
I
L
L
is typically set to 20% to 40% of the maximum
V
IN MIN
= Minimum input voltage
(
= Maximum output voltage
)
(µH)
V
•
10
15
33
33
68
33
47
68
15
33
68
L
OUT MAX
U
(
V
OUT MAX
(
MAX
DCR
0.44
0.58
1.00
0.38
0.52
0.45
0.73
0.40
0.22
0.51
0.84
(Ω)
(
U
)
• •
CURRENT
)
f L
RATING
–
0.35A
0.31A
0.43A
(mA)
300
300
310
600
500
440
360
400
L
V
), neglecting the drop
IN MIN
W
(
2
R power losses.
)
VENDOR
Murata
[phone]
www.murata.com
Panasonic
[phone]
www.panasonic.com
Toko
www.toko.com
Sumida
[phone]
www.sumida.com
)
U
Z5U. A 1µF input capacitor is sufficient for most applica-
tions. Always use a capacitor with sufficient voltage rating.
Table 2 shows a list of several ceramic capacitor manufac-
turers. Consult the manufacturers for detailed information
on their entire selection of ceramic parts.
Table 2. Ceramic Capacitor Manufacturers
Taiyo Yuden
AVX
Murata
INRUSH CURRENT
The LT3466-1 has built-in Schottky diodes. When supply
voltage is applied to the V
through the inductor and the Schottky diode and charges
up the output capacitor. Both Schottky diodes in the
LT3466-1 can sustain a maximum of 1A current. The
selection of inductor and capacitor value should ensure
the peak of the inrush current to be below 1A.
For low DCR inductors, which is usually the case for this
application, the peak inrush current can be simplified as
follows:
Table 3 gives inrush peak current for some component
selections.
Table 3. Inrush Peak Current
where
I
ω
PK
V
=
IN
12
=
:
5
5
5
5
9
(V)
V
LC
IN
1
ω
OUT
– .
L
0 6
L (µH)
15
33
47
68
47
33
IN
pin, an inrush current flows
[phone]
www.t-yuden.com
[phone]
www.avxcorp.com
[phone]
www.murata.com
C
OUT
0.47
1.00
1.00
0.47
0.22
2.2
(µF)
LT3466-1
I
0.78
0.77
0.95
0.53
0.84
0.93
P
11
(A)
34661f