Datasheet

Using the Evaluation Board
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Figure 4. Regulator Enables
6.2 Component Selection for SW1 and SW2
Table 1 shows ideal resistor values to establish buck voltages from 0.8V to 3.5V along with common
resistor values to establish these voltages. Common resistors do not always produce the target value;
error is given in the delta column. In addition to the resistor feedback, capacitor feedback C1 is always
required, and depending on the output voltage capacitor, C2 is also required. See Figure 5.
The output voltages of the bucks of the LM26480 are established by the feedback resistor dividers R1 and
R2 shown on Figure 5.
The equation for determining V
OUT
is:
V
OUT
= V
FB
× (R1 + R2)/R2 where V
FB
is the voltage on the Buck FBx pin.
The buck control loop will force V
FB
to be 0.50V ± 3%.
NOTE: Accuracy depends on device process corners, external components tolerance and matching,
and temperature.
4
AN-1800 Evaluation Kit for LM26480 - Dual DC/DC Buck Regulators with Dual SNVA329DMarch 2008Revised April 2013
Low-Noise Linear Regulators
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