SI-8050JD
Step-Down
to 5.0 V, 1.5 A,
DC/DC Converter
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 (TJ) in its
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-
ambient thermal resistance (RθJA).
Layout Guideline
The junction temperature (TJ) can be determined from
either of the following equations:
TJ = (PDRθJA) + TA
or
TJ = (PDRθJC) + TC
where PD = VIII – VOIO – VFIO(1 – [VO/VI])
or the adjacent graph,
VF = the Schottky diode forward voltage, and
RθJC =3°C/W.
115NortheastCutoff, Box15036
Worcester,Massachusetts01615-0036
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