2

IN

S

IN

S

V

V -V

L =

×

×

V

Iout_max×f

0.35

h

æ

ö

æ

ö

æ

ö

ç

÷

ç

÷

ç

÷

è

ø

è

ø

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ø

(1)

Rectifier Diode Selection

avg

out

I

I

=

TPS61085

Typically, it is recommended that the inductor current ripple is below 20% of the average inductor current. The

following equation can therefore be used to calculate the inductor value:

Table 1. Inductor Selection

L

COMPONENT

SIZE

DCR TYP

SUPPLIER

Isat (A)

CODE

(

µH)

(L×W×H mm)

(m

Ω)

1.2 MHz

3.3

Sumida

CDH38D09

4 x 4 x 1

240

1.25

4.7

Sumida

CDPH36D13

5 × 5 × 1.5

155

1.36

3.3

Sumida

CDPH4D19F

5.2 x 5.2 x 2

33

1.5

3.3

Sumida

CDRH6D12

6.7 x 6.7 x 1.5

62

2.2

4.7

Würth Elektronik

7447785004

5.9 × 6.2 × 3.3

60

2.5

5

Coilcraft

MSS7341

7.3 × 7.3 × 4.1

24

2.9

650 kHz

6.8

Sumida

CDP14D19

5.2 x 5.2 x 2

50

1

10

Coilcraft

LPS4414

4.3 × 4.3 × 1.4

380

1.2

6.8

Sumida

CDRH6D12/LD

6.7 x 6.7 x 1.5

95

1.25

10

Sumida

CDR6D23

5 × 5 × 2.4

133

1.75

10

Würth Elektronik

744778910

7.3 × 7.3 × 3.2

51

2.2

6.8

Sumida

CDRH6D26HP

7 x 7 x 2.8

52

2.9

To achieve high efficiency, a Schottky type should be used for the rectifier diode. The reverse voltage rating

Usually a Schottky diode with 2 A maximum average rectified forward current rating is sufficient for most

applications. The Schottky rectifier can be selected with lower forward current capability depending on the output

current times the diode forward voltage.

Typically the diode should be able to dissipate around 500mW depending on the load current and forward

voltage.

Table 2. Rectifier Diode Selection

CURRENT

COMPONENT

PACKAGE

Vr

SUPPLIER

RATING Iavg

CODE

TYPE

750 mA

20 V

0.425 V /

Fairchild Semiconductor

FYV0704S

SOT 23

750 mA

1 A

20 V

0.39 V / 1 A

NXP

PMEG2010AEH

SOD 123

1 A

20 V

0.52 V / 1 A

Vishay Semiconductor

B120

SMA

1 A

20 V

0.5 V / 1 A

Vishay Semiconductor

SS12

SMA

1 A

20 V

0.44 V / 1 A

Vishay Semiconductor

MSS1P2L

µ-SMP (Low

Profile)

10

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