Rectifier Diode Selection (Step-Down Converter)

Vout

D =

Vin

withIsw=minimumswitchcurrentofthe TPS65161(2.5 A)

(

)

Vout

I

=

I

Vin

1 - D x

= 1 -

x 2.5 A

avg

sw

æ

ö

ç

÷

è

ø

Output Capacitor Selection (Step-Down Converter)

TPS65161

TPS65161A, TPS65161B

To achieve high efficiency, a Schottky diode should be used. The reverse voltage rating should be higher than

the maximum output voltage of the step-down converter. The averaged rectified forward current at which the

Schottky diode needs to be rated is calculated as the off-time of the step-down converter times the maximum

switch current of the TPS65161:

Usually, a Schottky diode with 1.5-A or 2-A maximum average rectified forward current rating is sufficient for

most applications. Secondly, the Schottky rectifier has to be able to dissipate the power. The dissipated power is

the average rectified forward current times the diode forward voltage.

Table 6. Rectifier Diode Selection (Step-Down Converter)

CURRENT RATING

Vr

SIZE

COMPONENT SUPPLIER

3 A

20 V

0.36 V at 3 A

46°C/W

SMC

MBRS320, International Rectifier

2 A

20 V

0.44 V at 2 A

75°C/W

SMB

SL22, Vishay Semiconductor

2 A

20 V

0.5 V at 2 A

75°C/W

SMB

SS22, Fairchild Semiconductor

1.5 A

20 V

0.445 V at 1 A

88°C/W

SMA

SL12, Vishay Semiconductor

The device is designed to work with ceramic output capacitors. When using a 15-

µH inductor, two 22-µF ceramic

output capacitors are recommended. More capacitance can be added to improve the load transient response.

Table 7. Output Selection (Step-Down Converter)

CAPACITOR

VOLTAGE RATING

COMPONENT SUPPLIER

22

µF/0805

6.3 V

Taiyo Yuden JMK212BJ226MG

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Product Folder Link(s): TPS65161 TPS65161A TPS65161B