Power Rating Of Converter Stages - Microchip Technology Digital Power Starter Kit User Manual

2.7

POWER RATING OF CONVERTER STAGES

 2012 Microchip Technology Inc.
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The Digital Power Starter Kit is designed to be a self-contained power supply board with
variable 5W loads connected to each DC/DC converter.
2.7.1 BUCK CONVERTER
The Buck converter stage is rated for a maximum power output of 5W to the dedicated
on-board resistive load. The output voltage and output current should remain within its
Safe Operating Area (SOA) to avoid damage to the board, as shown in the graph in
Figure 2-4. The output voltage of the Buck converter (BUCK_Out) can be programmed
to be from a 1.2V to 4.5V output, with a default programmed voltage of 3.3V. The hard-
ware gain [5k/(3.3k + 5k)] of the voltage feedback from the BUCK_Out is provided by
the resistor divider network, R97 and R105. Additionally, a 20 Ohm resistor, R90, for
bode plot measurements is also in series with the feedback network. The hardware
gain of the current feedback is provided by the current transformer (T1) with turns ratio
(1:60) and burden resistor, R69.
FIGURE 2-4: BUCK CONVERTER SOA CURVE
Hardware
DS52078A-page 25