SI-8120JD Allegro Microsystems Inc, SI-8120JD Datasheet - Page 6

• Manufacturer Part Number: SI-8120JD
• Description: Regulator IC - Switching Mode (Surface Mount)
• Manufacturer: Allegro Microsystems Inc

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-
ambient thermal resistance (R
The junction temperature (T
either of the following equations:
or
where P
6
SI-8120JD
Step-Down
to 12.0 V, 1.5 A,
DC/DC Converter
or the adjacent graph,
V
R
D
F
JC
= V
= the Schottky diode forward voltage, and
=3°C/W.
I
I
I
– V
T
T
O
J
J
I
= (P
= (P
O
– V
D
D
J
R
) can be determined from
R
F
I
O
JA
JA
JC
(1 – [V
).
) + T
) + T
APPLICATIONS INFORMATION (cont.)
A
C
O
/V
I
])
J
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036
) in its
Layout Guideline