Datasheet

DI
L
+
V
O
V
I
V
I
* V
O
L ƒ
sw
DI
L(MAX)
+ I
O(MAX)
)
DI
L
2
TPS62620, TPS62621
TPS62622, TPS62623
TPS62624, TPS62625
www.ti.com SLVS848C –JULY 2009– REVISED AUGUST 2011
APPLICATION INFORMATION
INDUCTOR SELECTION
The TPS6262x series of step-down converters have been optimized to operate with an effective inductance
value in the range of 0.3μH to 1.3μH and with output capacitors in the range of 4.7μF to 10μF. The internal
compensation is optimized to operate with an output filter of L = 0.47μH and C
O
= 4.7μF. Larger or smaller
inductor values can be used to optimize the performance of the device for specific operation conditions. For more
details, see the CHECKING LOOP STABILITY section.
The inductor value affects its peak-to-peak ripple current, the PWM-to-PFM transition point, the output voltage
ripple and the efficiency. The selected inductor has to be rated for its dc resistance and saturation current. The
inductor ripple current (ΔI
L
) decreases with higher inductance and increases with higher V
I
or V
O
.
with: f
SW
= switching frequency (6 MHz typical)
L = inductor value
ΔI
L
= peak-to-peak inductor ripple current
I
L(MAX)
= maximum inductor current (1)
In high-frequency converter applications, the efficiency is essentially affected by the inductor AC resistance (i.e.
quality factor) and to a smaller extent by the inductor DCR value. To achieve high efficiency operation, care
should be taken in selecting inductors featuring a quality factor above 25 at the switching frequency. Increasing
the inductor value produces lower RMS currents, but degrades transient response. For a given physical inductor
size, increased inductance usually results in an inductor with lower saturation current.
The total losses of the coil consist of both the losses in the DC resistance
(DC)
) and the following
frequency-dependent components:
• The losses in the core material (magnetic hysteresis loss, especially at high switching frequencies)
• Additional losses in the conductor from the skin effect (current displacement at high frequencies)
• Magnetic field losses of the neighboring windings (proximity effect)
• Radiation losses
The following inductor series from different suppliers have been used with the TPS6262x converters.
Table 1. List of Inductors
MANUFACTURER SERIES DIMENSIONS
LQM21PN1R0NGR 2.0 x 1.2 x 1.0 max. height
LQM21PNR54MG0 2.0 x 1.2 x 1.0 max. height
MURATA LQM21PNR47MC0 2.0 x 1.2 x 0.55 max. height
LQM21PN1R0MC0 2.0 x 1.2 x 0.55 max. height
LQM21PN1R5MC0 2.0 x 1.2 x 0.55 max. height
HSLI-201210AG-R47 2.0 x 1.2 x 1.0 max. height
HITACHI METALS HSLI-201210SW-R85 2.0 x 1.2 x 1.0 max. height
JSLI-201610AG-R70 2.0 x 1.6 x 1.0 max. height
TOKO MDT2012-CX1R0A 2.0 x 1.2 x 1.0 max. height
FDK MIPS2012D1R0-X2 2.0 x 1.2 x 1.0 max. height
NM2012NR82 2.0 x 1.2 x 1.0 max. height
TAIYO YUDEN
NM20121NR0 2.0 x 1.2 x 1.0 max. height
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