Datasheet

LT3597
11
3597fa
Inductor Selection
Inductor values between 100µH and 470µH are recom-
mended for most applications. It is important to choose
an inductor that can handle the peak current without
saturating. The inductor DCR (copper wire resistance)
must also be low in order to minimize I
2
R power losses.
Table 1 lists several recommended inductors.
Table 1. Recommended Inductors
PART L (µH) DCR (Ω)
CURRENT
RATING (A) VENDOR
LPS6225
MSS1038
MSS1038
MSS1038
100
100
220
470
0.61
0.3
0.76
1.24
0.52
1.46
0.99
0.70
Coilcraft
www.coilcraft.com
CDRH105R
CDRW105R
CDRH105R
CDR6D28MN
100
220
470
100
0.253
0.50
1.29
0.9
1.35
0.94
0.60
0.75
Sumida
www.sumida.com
DS1262C2
DS1262C2
DS1262C2
100
220
470
0.17
0.35
1.243
1.5
1.0
0.7
Toko
www.toko.com
SLF10145T
SLF10145T
100
220
0.26
0.47
1.0
0.7
TDK
www.tdk.com
DR73
DR73
100
220
0.527
1.05
0.79
0.53
Coiltronics
www.cooperet.com
Capacitor Selection
Low ESR (equivalent series resistance) capacitors should
be used at the outputs to minimize output ripple voltage.
Use only X5R or X7R dielectrics, as these materials retain
their capacitance over wider voltage and temperature
ranges than other dielectrics. Table 2 lists some suggested
manufacturers. Consult the manufacturers for detailed
information on their entire selection of ceramic surface
mount parts.
Table 2. Recommended Ceramic Capacitor Manufacturers
Taiyo Yuden
www.t-yuden.com
AVX www.avxcorp.com
Murata www.murata.com
Kemet www.kemet.com
TDK www.tdk.com
applicaTions inForMaTion
Typically 10µF capacitors are sufficient for the V
IN
and BIAS
pins. The output capacitor for the buck regulators depends
on the number of LEDs and switching frequency. Refer to
Table 3 for the proper output capacitor selection.
Table 3. Recommended Output Capacitor Values (V
LED
= 3.5V)
SWITCHING FREQUENCY (kHz) # LEDS C
OUT
(µF)
1000 1-3 3.3
>3 2.2
500 1-3 4.7
>3 3.3
200 1-3 15
>3 6.8
Diode Selection
Schottky diodes, with their low forward voltage drop and
fast switching speed, must be used for all LT3597 ap-
plications. Do not use P-N junction diodes. The diode’s
average current rating must exceed the application’s aver-
age current. The diode’s maximum reverse voltage must
exceed the application’s input voltage. Table 4 lists some
recommended Schottky diodes.
Table 4. Recommended Diodes
PART
MAX CURRENT
(A)
MAX REVERSE
VOLTAGE (V) MANUFACTURER
DFLS160
B160
1
1
60
60
Diodes, Inc.
www.diodes.com
CMMSH1-60 1 60 Central
www.centralsemi.com
ESIPB 1 100 Vishay
www.vishay.com