R5975D datasheet(27/47 Pages) STMICROELECTRONICS

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R5975D

Application information

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 13.

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 pick-up noise. Another important issue is the ground plane of the board. As the

package has an exposed pad, it is very important to connect it to an extended ground plane

in order to reduce the thermal resistance junction to ambient.

Figure 13. Layout example

8.3

Thermal considerations

8.3.1

Thermal resistance RTHJ-A

RTHJ-A is the equivalent static thermal resistance junction to ambient of the device; it can be

calculated as the parallel of many paths of heat conduction from the junction to the ambient.

For this device, the path through the exposed pad is the one conducting the largest amount

of heat. The static RTHJ-A measured on the application is about 40 °/W.

The junction temperature of the device is:

Equation 22

TA RthJA PTOT

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R5975D Datasheet(PDF) 27 Page - STMicroelectronics