LTC3524

12

3524f

APPLICATIONS INFORMATION

Inductor Selection

3.3μH to 15μH inductors are recommended for use with

the LTC3524’s two boost converters. The synchronous

LCD bias boost inductor should have a saturation current

white LED boost inductor should have a rating of at least

600mA. In most applications, the inductor value for the

LCD bias will be larger (10μH to 15μH) to prevent opera-

tion in deep discontinuous mode. The inductor value for

the white LED can be smaller (3.3μH to 6.8μH), since it

operates at higher currents. Ferrite core materials are

strongly recommended for their superior high frequency

performance characteristics. Inductors meeting these

requirements are listed in Table 1. The maximum current

and DCR ranges in the table correspond to the respec-

tive Inductance range (for example, the 3.3μH inductor

Table 1. Recommended Inductors

PART

L

(μH)

MAXIMUM

CURRENT

(mA)

DCR (Ω)

DIMENSIONS

(mm)

(L × W × H)

MANUFACTURER

ME3220

LP03010

MSS4020

3.3-15

3.3-10

3.3-15

1300-700

950-570

1100-440

0.14-0.52

0.2-0.52

0.09-0.33

3.2 × 2.5 × 2.0

3.0 × 3.0 × 1.0

4.0 × 4.0 × 2.0

Coil Craft

www.coilcraft.com

SD3112

3.3-15

970-405

0.16-0.65

3.1 × 3.1 × 1.2

Cooper

www.cooperet.com

MIP3226D

3-10

1000-200

0.1-0.16

3.2 × 2.6 × 1.0

FDK

www.fdk.com

LQH32CN

LQH2MC

4.7-15

4.7-15

650-300

300-200

0.15-0.58

0.8-1.6

3.2 × 2.5 × 1.5

2 × 1.6 × 0.9

Murata

www.murata.com

CDRH3D16

CDRH2D14

3.3-15

3.3-12

1100-520

820-420

0.09-0.41

0.12-0.32

3.8 × 3.8 × 1.8

3.2 × 3.2 × 1.5

Sumida

www.sumida.com

NR3010

NR3015

3.3-15

3.3-15

750-400

1200-560

0.16-0.74

0.1-0.36

3.0 × 3.0 × 1.0

3.0 × 3.0 × 1.5

Taiyo Yuden

www.t-yuden.com

will have the highest maximum current and lowest DCR).

Shielded inductor series parts are in bold text.

2.2μF using a low impedance connection to the battery.

The VLED output capacitor should be X5R type and at least

1μF for analog dimming and 4.7μF for PWM dimming.

2.2μF and 10μF. A larger capacitor (10μF) should be used

if lower output ripple is desired or the output load required

is close to the 25mA maximum.

specified performance. Ceramic X5R types are strongly

recommended for their low ESR and ESL and capacitance

vs bias voltage stability. The filter capacitors on V2x, VN,