SI-8090JD

Step-Down

to 9.0 V, 1.5 A,

DC/DC Converter

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036

Switching

Regulators

6

Layout Guideline

APPLICATIONS INFORMATION (cont.)

Thermal Protection. Circuitry turns off the switching

transistor when the junction temperature rises above 150°C.

It is intended only to protect the device from failures due to

excessive junction temperatures and should not imply that

output short circuits or continuous overloads are permitted.

Heat Radiation and Reliability. The reliability of the

IC is directly related to the junction temperature (T

operation. Accordingly, careful consideration should be

given to heat dissipation.

The inner frame on which the integrated circuit is mounted

is connected to the GND terminal (pin 3). Therefore, it is

very effective for heat radiation to enlarge the copper area

that is connected to the GND terminal. The graph illus-

trates the effect of the copper area on the junction-to-

The junction temperature (T

either of the following equations:

T

or

T

where P

or the adjacent graph,

V