AMC2596
Heat Sink and Thermal Consideration
Although the AMC2596 requires only a small heat sink for most cases, the following thermal consideration is
important for all operation. With the package thermal resistances
θ
JA
and
θ
JC
, total power dissipation can be estimated
as follows:
P
D
= (V
IN
×
I
Q
)+(V
OUT
/ V
IN
)(I
LOAD
×
V
SAT
);
When no heat sink is used, the junction temperature rise can be determined by the following:
∆T
J
= P
D
× θ
JA
;
With the ambient temperature, the actual junction temperature will be:
T
J
=
∆T
J
+T
A
;
If the actual operating junction temperature is out of the safe operating junction temperature (typically 125°C), then a
heat sink is required. When using a heat sink, the junction temperature rise will be reduced by the following:
∆T
J
= P
D
×
(θ
JC
+
θ
interface
+
θ
Heat sink
);
As one can see from the above, it is important to choose an heat sink with adequate size and thermal resistance, such
that to maintain the regulator’s junction temperature below the maximum operating temperature.
Copyright
©
2006 ADDtek Corp.
9
DD008_A --
JUNE 2006
ADDTEK [ ADDTEK CORP ]
