Datasheet

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1
8.0
18.0
1
21
2
1
2
1
_
V
V
RR
R
R
VV
R
R
VV
OUT
OUT
FBREFOUT
TPS62125
www.ti.com SLVSAQ5C –MARCH 2012–REVISED DECEMBER 2013
APPLICATION INFORMATION
OUTPUT VOLTAGE SETTING
The output voltage can be calculated by:
(5)
The internal reference voltage for the error amplifier, V
REF_FB
, is nominal 0.808V. However for the feedback
resistor divider selection, it is recommended to use the value 0.800V as the reference. Using this value, the
output voltage sets 1% higher and provides more headroom for load transients as well for line and load
regulation. The current through the feedback resistors R
1
and R
2
should be higher than 1µA. In applications
operating over full temperature range or in noisy environments, this current may be increased for robust
operation. However, higher currents through the feedback resistors impact the light load efficiency of the
converter.
Table 2 shows a selection of suggested values for the feedback divider network for most common output
voltages.
Table 2. Suggested Values for Feedback Divider Network
Output Voltage 1.2V 1.8V 3.3V 5V 6.7V 8V
R1 [kΩ] 180 300 1800 1100 1475 1800
R2 [kΩ] 360 240 576 210 200 200
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