TPS62050 Datasheet, PDF (17/21 Pages) Texas Instruments – 800-mA SYNCHRONOUS STEP-DOWN CONVERTER

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TPS62050, TPS62051
TPS62052, TPS62054, TPS62056
SLVS432D – SEPTEMBER 2002 – REVISED OCTOBER 2003
APPLICATION INFORMATION (continued)
INDUCTOR SELECTION
A 10-µH minimum inductor should be used with the TPS6205x. Values larger than 22 µH or smaller than 10 µH
may cause stability problems due to the internal compensation of the regulator. After choosing the inductor value
of typically 10 µH, two additional inductor parameter should be considered: the current rating of the inductor and
the dc resistance. The dc resistance of the inductance directly influences the efficiency of the converter.
Therefore, an inductor with lowest dc resistance should be selected for highest efficiency. In order to avoid
saturation of the inductor, the inductor should be rated at least for the maximum output current plus half the
inductor ripple current which is calculated as:
DI_L + V_O
1
*
VO
VI
Lf
I_L(max)
+
I_O(max)
)
DIL
2
f = Switching frequency (850 kHz typical)
L = Inductor value
∆IL = Peak-to-peak inductor ripple current
I_L(max) = Maximum inductor current
The highest inductor current occurs at maximum VIN . A more conservative approach is to select the inductor
current rating just for the maximum switch current of the TPS6205x which is 1.4 A maximum. See Table 2 for
inductors that have been tested for operation with the TPS6205x.
MANUFACTURER
TDK
Sumida
Coilcraft
Wuerth
TYPE
SLF7032T-
100M1R4SLF7032T-
220M96SLF7045T-
100M1R3SLF7045T-
100MR90
CDR74B
CDR74B
CDH74
CDH74
CDR63B
CDRH4D28
CDRH5D28
CDRH5D18
DT3316P-153
DT3316P-223
WE-PD 744 778 10
WE-PD 744 777 10
WE-PD 744 778 122
WE-PD 744 777 122
Table 2. Inductors
INDUCTANCE
10 µH ±20%22 µH ±20%10
µH ±20%22 µH ±20%
DC RESISTANCE
53 mΩ±20%110
mΩ±20%36
mΩ±20%61 mΩ±20%
SATURATION CURRENT
1.4 A0.96 A1.3 A0.9 A
10 µH
22 µH
10 µH
22 µH
10 µH
10 µH
10 µH
10 µH
15 µH
22 µH
10 µH
10 µH
22 µH
22 µH
70 mΩ
130 mΩ
49 mΩ
110 mΩ
140 mΩ
128 mΩ
48 mΩ
92 mΩ
60 mΩ
84 mΩ
72 mΩ
49 mΩ
190 mΩ
110 mΩ
1.65 A
1.12 A
1.8 A
1.23 A
1A
1A
1.3 A
1.2 A
1.8 A
1.5 A
1.68 A
1.84 A
1.07A
1.23 A
17