Datasheet

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APPLICATION INFORMATION
Output Voltage Setting
Converter 1 (DCDC1)
R2
R1
V =
O
V x1+
ref
()
(4)
Converter 2 (DCDC2)
VINDCDC1/2
ENDCDC2
PGND
VDCDC2
L2
Vbat
1 W
1 Fm
C
I
C
O
V
O
L
R3
R4
V
CC
DEFDCDC2
AGND
TPS65050, TPS65051, TPS65052
TPS65054, TPS65056
SLVS710A – JANUARY 2007 – REVISED AUGUST 2007
The output voltage of converter 1 can be set by an external resistor network. The output voltage can be
calculated using Equation 4 .
with an internal reference voltage V
ref
, 0.6 V .
Setting the total resistance of R1 + R2 to less than 1 M Ω is recommended. The resistor network connects to the
input of the feedback amplifier, therefore, requiring a small feedforward capacitor in parallel to R1. A typical value
of 47 pF is sufficient.
The output voltage of converter 2 can be selected as following:
• Adjustable output voltage defined with external resistor network on pin DEFDCDC2. This option is available
for TPS65050 and TPS65051.
• Two default fixed output voltages selectable by pin DEFDCDC2, see Table 2 . This option is available for
TPS65052 and TPS65054.
Table 2. Default Fixed Output Voltages
Converter 2 DEFDCDC2 = low DEFDCDC2 = high
TPS65050 -- --
TPS65051 -- --
TPS65052 1 V 1.3 V
TPS65054 1.3 V 1.05 V
TPS65056 1 V 1.3 V
The adjustable output voltage can be calculated similar to the DCDC1 converter. Setting the total resistance of
R3 + R4 to less than 1 M Ω is recommended. Route the DEFDCDC2 line separate from noise sources, such as
the inductor or the L2 line. The VDCDC2 line needs to be directly connected to the output capacitor. As the
VDCDC2 line is the feedback to the internal amplifier, no feedforward capacitor at R3 is needed.
Using an external resistor divider at DEFDCDC2:
Figure 23. External Resistor Divider
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Product Folder Link(s): TPS65050, TPS65051, TPS65052 TPS65054, TPS65056