Datasheet

withIsw=minimumswitchcurrentofthe TPS65161(2.5 A)
( )
Vout
I = I
Vin
1 - D x = 1 - x 2.5 A
avg sw
æ ö
ç ÷
è ø
Vout
D =
Vin
TPS65161
TPS65161A, TPS65161B
www.ti.com SLVS617E –APRIL 2006–REVISED MARCH 2013
Rectifier Diode Selection (Step-Down Converter)
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.
P
D
= I
avg
× V
F
= Isw × (1 – D) × V
F
with Isw = minimum switch current of the TPS65161 (2.5 A). (1)
Table 6. Rectifier Diode Selection (Step-Down Converter)
CURRENT RATING
Vr V
forward
R
θJA
SIZE COMPONENT SUPPLIER
I
avg
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
Output Capacitor Selection (Step-Down Converter)
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
Copyright © 2006–2013, Texas Instruments Incorporated Submit Documentation Feedback 21
Product Folder Links: TPS65161 TPS65161A TPS65161B