Datasheet

DI
L
+ Vout
1 *
Vout
Vin
L ƒ
I
Lmax
+ I
outmax
)
DI
L
2
TPS65023, TPS65023B
SLVS670J –JUNE 2006– REVISED SEPTEMBER 2011 www.ti.com
LDO_CTRL. Register Address: 08h (read/write) Default Value: set with DEFLDO1 and DEFLDO2
LDO_CTRL B7 B6 B5 B4 B3 B2 B1 B0
Bit name and RSVD RSVD
LDO2_2 LDO2_1 LDO2_0 LDO1_2 LDO1_1 LDO1_0
function
Default DEFLDOx DEFLDOx DEFLDOx DEFLDOx DEFLDOx DEFLDOx
Default value
UVLO UVLO UVLO UVLO UVLO UVLO
loaded by:
Read/Write R/W R/W R/W R/W R/W R/W
The LDO_CTRL registers are used to set the output voltage of LDO1 and LDO2. LDO_CTRL[7] and
LDO_CTRL[3] are reserved and should always be written to 0.
The default voltage is set with DEFLDO1 and DEFLDO2 pins as described in Table 3.
LDO2 OUTPUT LDO1 OUTPUT
LDO2_2 LDO2_1 LDO2_0 LDO1_2 LDO1_1 LDO1_0
VOLTAGE VOLTAGE
0 0 0 1.05 V 0 0 0 1 V
0 0 1 1.2 V 0 0 1 1.1 V
0 1 0 1.3 V 0 1 0 1.3 V
0 1 1 1.8 V 0 1 1 1.8 V
1 0 0 2.5 V 1 0 0 2.2 V
1 0 1 2.8 V 1 0 1 2.6 V
1 1 0 3.0 V 1 1 0 2.8 V
1 1 1 3.3 V 1 1 1 3.15 V
DESIGN PROCEDURE
Inductor Selection for the DC-DC Converters
Each of the converters in the TPS65023, TPS65023B typically use a 2.2 μH output inductor. Larger or smaller
inductor values are used to optimize the performance of the device for specific operation conditions. The
selected inductor has to be rated for its dc resistance and saturation current. The dc resistance of the inductance
influences directly the efficiency of the converter. Therefore, an inductor with lowest dc resistance should be
selected for highest efficiency.
For a fast transient response, a 2.2-μH inductor in combination with a 22-μF output capacitor is recommended.
Equation 5 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 5. This is needed
because during heavy load transient the inductor current rises above the value calculated under Equation 5.
(4)
(5)
with:
f = Switching Frequency (2.25 MHz typical)
L = Inductor Value
ΔI
L
= Peak-to-Peak inductor ripple current
I
LMAX
= Maximum Inductor current
The highest inductor current occurs at maximum Vin.
Open core inductors have a soft saturation characteristic, and they can usually handle higher inductor currents
versus a comparable shielded inductor.
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