Datasheet
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APPLICATION INFORMATION
DESIGN PROCEDURE
Programming the Output Voltage
DC/DC Converter
R3 + R6
ǒ
V
O
V
FB
* 1
Ǔ
+ 180 kW
ǒ
V
O
500 mV
* 1
Ǔ
(1)
C
parR3
+ 20 pF
ǒ
200 kW
R6
* 1
Ǔ
(2)
SWN
C3
10 µF
Power
Supply
R1
R2
VBAT
VOUT
FB
R3
R6
LDOIN
R5
R4
LDOSENSE
LDOOUT
R7 R9
C6
2.2 µF
C4
100 µF
U1
LBO
PGOOD
PGND
LBI
SKIPEN
EN
LDOEN
GND
TPS6113xPW
V
CC1
SEPICOutput
V
CC2
LDOOutput
Control
Outputs
C5
2.2 µF
L1−A
22 µH
SWP
C7
L1−B
22 µH
10 µF
TPS61130
TPS61131
TPS61132
SLVS431B – JUNE 2002 – REVISED JANUARY 2008
The TPS6113x dc/dc converters are intended for systems powered by a dual up to 4 cell NiCd or NiMH battery
with a typical terminal voltage between 1.8 V and 6.5 V. They can also be used in systems powered by one-cell
Li-Ion with a typical stack voltage between 2.5 V and 4.2 V. Additionally, two up to four primary alkaline battery
cells can be the power source in systems where the TPS6113x is used.
The output voltage of the TPS61130 dc/dc converter section can be adjusted with an external resistor divider.
The typical value of the voltage on the FB pin is 500 mV. The maximum recommended value for the output
voltage is 5.5 V. The current through the resistive divider should be about 100 times greater than the current into
the FB pin. The typical current into the FB pin is 0.01 µ A and the voltage across R6 is typically 500 mV. Based
on those two values, the recommended value for R6 should be lower than 500 k Ω , in order to set the divider
current at 1 µ A or higher. Because of internal compensation circuitry the value for this resistor should be in the
range of 200 k Ω . From that, the value of resistor R3, depending on the needed output voltage (V
O
), can be
calculated using Equation 1 :
If as an example, an output voltage of 3.3 V is needed, a 1-M Ω resistor should be chosen for R3. If for any
reason the value for R6 is chosen significantly lower than 200 k Ω additional capacitance in parallel to R3 is
recommended. The required capacitance value can be easily calculated using Equation 2 .
Figure 24. Typical Application Circuit for Adjustable Output Voltage Option
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