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R5972D

Application information

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8.2

Layout considerations

The layout of switching DC-DC converters is very important to minimize noise and

interference. Power-generating portions of the layout are the main cause of noise and so

high switching current loop areas should be kept as small as possible and lead lengths as

short as possible.

High impedance paths (in particular the feedback connections) are susceptible to

interference, so they should be as far as possible from the high current paths. A layout

example is provided in Figure 11.

The input and output loops are minimized to avoid radiation and high frequency resonance

problems. The feedback pin connections to the external divider are very close to the device

to avoid pickup noise.

Figure 11. Layout example

8.3

Thermal considerations

The dissipated power of the device is tied to three different sources:



Equation 22

Where D is the duty cycle of the application. Note that the duty cycle is theoretically given by





2

D



=