Datasheet

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SW1
FB1
SW2
ADJ2
DEF_1
VIN3.3V – 6V
VIN
EN_1
EN_2
MODE/
DATA
TPS62410
GND
L1
C
10 F
IN
m
2.2 Hm
R11
270kW
R12
180kW
V =1.5V
upto800mA
OUT1
C =10 F
OUT1
m
V =2.85V
upto800mA
OUT2
L2
C
ff2
33pF
3.3 Hm
R21
825kW
R22
220kW
C =10 F
OUT2
m
OUTPUT FILTER DESIGN (INDUCTOR AND OUTPUT CAPACITOR)
Inductor Selection
DI
L
+ Vout
1 *
Vout
Vin
L ƒ
(6)
I
Lmax
+ I
outmax
)
DI
L
2
(7)
TPS62410
SLVS737 – FEBRUARY 2007
APPLICATION INFORMATION (continued)
Figure 34. Typical Application Circuit 1.5V/2.85V Adjustable Outputs
The device is optimized to operate with inductors of 2.2 µ H to 4.7 µ H and output capacitors of 10 µ F to 22 µ F.
For operation with a 2.2 µ H inductor, a 22 µ F capacitor is suggested.
The selected inductor has to be rated for its DC resistance and saturation current. The DC resistance of the
inductance will influence directly the efficiency of the converter. Therefore an inductor with lowest DC resistance
should be selected for highest efficiency.
Equation 6 calculates the maximum inductor current under static load conditions. The saturation current of the
inductor should be rated higher than the maximum inductor current as calculated with Equation 7 . This is
recommended because during heavy load transient the inductor current will rise above the calculated value.
With:
f = Switching Frequency (2.25MHz typical)
L = Inductor Value
∆ I
L
= Peak to Peak inductor ripple current
I
Lmax
= Maximum Inductor current
The highest inductor current will occur at maximum Vin.
Open core inductors have a soft saturation characteristic and they can usually handle higher inductor currents
versus a comparable shielded inductor.
A more conservative approach is to select the inductor current rating just for the maximum switch current of the
corresponding converter. It must be considered, that the core material from inductor to inductor differs and will
have an impact on the efficiency especially at high switching frequencies.
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