Texas Instruments LM20133, User Manual

Page: 6 / 8

R
FB1
= - 1
V
OUT
0.8
x R
FB2
PCB Layout
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5.10 R
FB1
and R
FB2
The resistors labeled R
FB1
and R
FB2
create a voltage divider from V
OUT
to the feedback pin that is used to
set the output of the voltage regulator. Nominally, the output of the LM20133 evaluation board is set to 1.2
V, giving resistor values of R
FB1
= 4.99 k Ω and R
FB2
= 10 k Ω . If a different output voltage is required, the
value of R
FB1
can be adjusted according to Equation 9 :
(9)
R
FB2
does not need to be changed from its value of 10 k Ω .
6 PCB Layout
Figure 2. Top Layer
6 AN-1688 LM20133 Evaluation Board SNVA274B – October 2007 – Revised May 2013
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