LTC3429/LTC3429B

9

3429fa

The inductor current ripple is typically set for 20% to 40%

ferrite core inductor materials reduce frequency

dependent power losses compared to cheaper powdered

iron types, improving efficiency. The inductor should have

low ESR (series resistance of the windings) to reduce the

inductor current without saturating. Molded chokes and

some chip inductors usually do not have enough core to

support the peak inductor currents of 850mA seen on the

LTC3429/LTC3429B. To minimize radiated noise, use a

toroid, pot core or shielded bobbin inductor. See Table 1

for some suggested components and suppliers.

Table 1. Recommended Inductors

MAX

L

DCR

HEIGHT

PART

(µH)

mΩ

(mm)

VENDOR

CDRH5D18-4R1

4.1

57

2.0

Sumida

CDRH5D18-100

10

124

2.0

www.sumida.com

CDRH3D16-4R7

4.7

105

1.8

CDRH3D16-6R8

170

1.8

CR43-4R7

4.7

109

3.5

CR43-100

10

182

3.5

CMD4D06-4R7MC

4.7

216

0.8

CMD4D06-3R3MC

3.3

174

0.8

DS1608-472

4.7

60

2.9

Coilcraft

DS1608-103

10

75

2.9

www.coilcraft.com

DO1608C-472

4.7

90

2.9

D52LC-4R7M

4.7

84

2.0

Toko

D52LC-100M

10

137

2.0

www.tokoam.com

LQH32CN4R7M24

4.7

195

2.2

Murata

www.murata.com

Output and Input Capacitor Selection

Low ESR (equivalent series resistance) capacitors should

be used to minimize the output voltage ripple. Multilayer

ceramic capacitors are an excellent choice as they have

extremely low ESR and are available in small footprints. A

4.7µF to 15µF output capacitor is sufficient for most

applications. Larger values up to 22µF may be used to

obtain extremely low output voltage ripple and improve

transient response. An additional phase lead capacitor

may be required with output capacitors larger than 10µF

to maintain acceptable phase margin. X5R and X7R

dielectric materials are preferred for their ability to main-

tain capacitance over wide voltage and temperature ranges.

Low ESR input capacitors reduce input switching noise

and reduce the peak current drawn from the battery. It

follows that ceramic capacitors are also a good choice for

input decoupling and should be located as close as pos-

sible to the device. A 10µF input capacitor is sufficient for

virtually any application. Larger values may be used with-

out limitations. Table 2 shows a list of several ceramic

capacitor manufacturers. Consult the manufacturers di-

rectly for detailed information on their entire selection of

ceramic capacitors.

Table 2. Capacitor Vendor Information

SUPPLIER

WEBSITE

AVX

www.avxcorp.com

Murata

www.murata.com

Taiyo Yuden

www.t-yuden.com

APPLICATIO S I FOR ATIO