LTC3400/LTC3400B

7

3400f

Table 1. Recommended Inductors

MAX

L

DCR

HEIGHT

PART

(

µH)

m

Ω

(mm)

VENDOR

CDRH5D18-4R1

4.1

57

2.0

Sumida

CDRH5D18-100

10

124

2.0

(847) 956-0666

CDRH3D16-4R7

4.7

105

1.8

www.sumida.com

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

(847) 639-6400

DO1608C-472

4.7

90

2.9

www.coilcraft.com

D52LC-4R7M

4.7

84

2.0

Toko

D52LC-100M

10

137

2.0

(408) 432-8282

www.tokoam.com

LQH3C4R7M24

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

2.2

µF to 10µF output capacitor is sufficient for most

applications. Larger values up to 22

µF 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 10

µF

APPLICATIO S I FOR ATIO

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 4.7

µF 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 parts.

Table 2. Capacitor Vendor Information

SUPPLIER

PHONE

WEBSITE

AVX

(803) 448-9411

www.avxcorp.com

Murata

(714) 852-2001

www.murata.com

Taiyo Yuden

(408) 573-4150

www.t-yuden.com

Output Diode

Use a Schottky diode such as an MBR0520L, CMDSH2-3,

1N5817 or equivalent if the converter output voltage is 4.5V

or greater. The Schottky diode carries the output current for

the time it takes for the synchronous rectifier to turn on. Do

not use ordinary rectifier diodes, since the slow recovery

times will compromise efficiency. A Schottky diode is

optional for output voltages below 4.5V, but will increase

converter efficiency by 2% to 3%.