Datasheet

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APPLICATION INFORMATION
Design Procedure
Programming the Output Voltage
R1  R2 

V
POS
V
REF
 1

(1)
V
POS
V
NEG
Q1
L1
D1
C1
4.7 F
U1
C2
4.7 F
C3
0.1 F
VPOS
FBP
VREF
FBN
VNEG
OUTN
CP
CN
PGND
INP
BSW
INN
VIN
ENP
PSP
ENN
PSN
GND
TPS65130
R1
R2
C4
4x4.7 F
R4
R3
D2
C8
0.22 F
L2
4.7 H
C7
C6
R7
4.7 H
R8
C9
R9
C10
V
IN
C5
4x4.7 F
TPS65130, TPS65131
SLVS493B – MARCH 2004 – REVISED SEPTEMBER 2004
The TPS65130/1 dc-dc converter is intended for systems typically powered by a single-cell Li-ion or Li-polymer
battery with a terminal voltage between 2.7 V up to 4.2 V. Because the recommended input voltage goes up to
5.5 V, the device is also suitable for 3-cell alkaline, NiCd, or NiMH batteries, as well as any regulated supply
voltages between 2.7 V and 5.5 V. It provides two independent output voltage rails which are programmed as
follows.
Boost Converter
The output voltage of the TPS65130/1 boost converter stage can be adjusted with an external resistor divider
connected to the FBP pin. The typical value of the voltage at the FBP pin is the reference voltage, which is 1.213
V. The maximum recommended output voltage at the boost converter is 15 V. To achieve appropriate accuracy,
the current through the feedback divider should be about 100 times higher than the current into the FBP pin.
Typical current into the FBP pin is 0.05 µA, and the voltage across R
2
is 1.213 V. Based on those values, the
recommended value for R
2
should be lower than 200 k Ω in order to set the divider current at 5 µA or higher.
Depending on the needed output voltage (V
POS
), the value of the resistor R
1
can then be calculated using
Equation 1 :
As an example, if an 8-V output is needed, and a resistor of 180 k Ω has been chosen for R
2
, a 1-M Ω resistor is
needed to program the desired output voltage.
Inverting Converter
The output voltage of the TPS65130/1 inverting converter stage can also be adjusted with an external resistor
divider. It must be connected to the FBN pin. In difference to the feedback divider at the boost converter, the
reference point of the feedback divider is not GND; it is V
REF
. So the typical value of the voltage at the FBN pin is
0 V. The minimum recommended output voltage at the inverting converter is –15 V. Feedback divider current
23