Datasheet

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Output Capacitor Selection
Input Capacitor Selection
Rectifier Diode Selection
D  1 
Vin
Vout
(8)
I
avg
 (1  D)  Isw 
Vin
Vout
 2.0 A with lsw  minimum switch current
of the TPS65150 (2.0 A)
(9)
TPS65150
SLVS576 – SEPTEMBER 2005
DETAILED DESCRIPTION (continued)
Table 1. Inductor Selection
INDUCTOR VALUE COMPONENT SUPPLIER DIMENSIONS IN mm Isat – DC Resistance
4.7 µH Coilcraft DO1813P-472HC 8,89 × 6,1 × 5,0 2.6 A – 54 m Ω
4.2 µH Sumida CDRH5D28 4R2 5,7 × 5,7 × 3 2.2 A – 23 m Ω
4.7 µH Sumida CDC5D23 4R7 6 × 6 × 2,5 1.6 A – 48 m Ω
4.2 µH Sumida CDRH6D12 4R2 6,5 × 6,5 × 1,5 1.8 A – 60 m Ω
3.9 µH Sumida CDRH6D28 3R9 7,0 × 7,0 × 3,0 2.6A – 20 m Ω
3.3 µH Sumida CDRH6D12 4R2 6,5 × 6,5 × 1,5 1.9 A – 50 m Ω
For best output voltage filtering, a low ESR output capacitor is recommended. Ceramic capacitors have a low
ESR value, but tantalum capacitors can be used as well, depending on the application. A 22-µF ceramic output
capacitor works for most applications. Higher capacitor values can be used to improve the load transient
regulation. See Table 2 for the selection of the output capacitor.
For good input voltage filtering, low ESR ceramic capacitors are recommended. A 22-µF ceramic input capacitor
is sufficient for most applications. For better input voltage filtering, this value can be increased. See Table 2 , and
Typical Applications for input capacitor recommendations.
Table 2. Input and Output Capacitor Selection
CAPACITOR VOLTAGE RATING COMPONENT SUPPLIER COMMENTS
22 µF/1206 16 V Taiyo Yuden EMK325BY226MM Cout
22 µF/1206 6.3 V Taiyo Yuden JMK316BJ226 Cin
To achieve high efficiency, a Schottky diode should be used. The reverse voltage rating should be higher than
the maximum output voltage of the converter. The required average rectified forward current rating of the
Schottky diode is calculated as the off time of the converter times the maximum switch current of the TPS65150:
Usually, a Schottky diode with 1-A maximum average rectified forward current rating is sufficient for most of the
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.
PD = Iavg × VF = Isw × (1 – D) × VF with lsw = minimum switch current of the TPS65150 (2.0 A).
Typically, the diode should be able to dissipate 270 mW maximum depending on the load current and forward
voltage. In terms of efficiency, the main parameters of the diode are the forward voltage and the reverse leakage
current of the diode; both should be as low as possible.
Table 3. Rectifier Diode Selection
CURRENT RATING Vr V
forward
COMPONENT SUPPLIER
Iavg
2 A 20 V 0.44 V at 2 A SL22, Vishay Semiconductor
2 A 20 V 0.5 V at 2 A SS22, Fairchild Semiconductor
1 A 30 V 0.44 V at 2 A MBRS130L, Fairchild Semiconductor
1 A 20 V 0.45 V at 1 A UPS120, Microsemi
1 A 20 V 0.45 V at 1 A MBRM120, ON Semiconductor
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