HCPL-316 ETC, HCPL-316 Datasheet - Page 30

• Manufacturer Part Number: HCPL-316
• Description: 2.0 Amp Gate Drive Optocoupler with Integrated (VCE) Desaturation Detection and Fault Status Feedback
• Manufacturer: ETC

Thermal Model
The HCPL-316J is designed to
dissipate the majority of the heat
through pins 4 for the input IC
and pins 9 and 10 for the output
IC. (There are two V
the output side, pins 9 and 10,
for this purpose.) Heat flow
through other pins or through the
package directly into ambient are
considered negligible and not
modeled here.
In order to achieve the power
dissipation specified in the
absolute maximum specification,
it is imperative that pins 4, 9, and
10 have ground planes connected
to them. As long as the maximum
power specification is not
exceeded, the only other limita-
tion to the amount of power one
can dissipate is the absolute
maximum junction temperature
specification of 125 C. The
junction temperatures can be
calculated with the following
equations:
T
T
where P
and P
Figure 78. HCPL-316J Thermal Model.
ji
jo
4A
i4
= P
= P
= 60°C/W
= 50°C/W*
o
= power into output IC.
i
o
(
i
(
= power into input IC
i4
o9,10
T
T
P4
ji
+
+
4A
T
A
) + T
9,10A
T
EE
P9,10
T
jo
pins on
9,10A
A
) + T
O9,10
= 50°C/W*
= 30°C/W
A
Since
dependent on PCB layout and
airflow, their exact number may
not be available. Therefore, a
more accurate method of calcu-
lating the junction temperature is
with the following equations:
T
T
These equations, however,
require that the pin 4 and pins
9,10 temperatures be measured
with a thermal couple on the pin
at the HCPL-316J package edge.
From the earlier power
dissipation calculation
example:
P
= 100 C, and assuming the
thermal model shown in Figure
77 below.
T
T
both of which are within the
absolute maximum specification
of 125 C.
i
ji
jo
ji
jo
T
T
T
T
*The
reasonable air flow. This value may increase or decrease by a factor of 2 depending
on PCB layout and/or airflow.
+ 50 C/W) + 100 C = 110 C
+ 50 C/W) + 100 C = 119 C
= 90.8 mW, P
= (90.8 mW)(60 C/W
I4
I9,10
4A
9,10A
= P
ji
jo
P4
P9,10
= (240 mW)(30 C/W
= P
= junction temperature of input side IC
= junction temperature of output side IC
= input side IC to pin 4 thermal resistance
= pin 4 temperature at package edge
= pin 4 to ambient thermal resistance
4A
i i4
4A
o o9,10
= output side IC to pin 9 and 10 thermal resistance
= pin 9 and 10 to ambient thermal resistance
= pin 9 and 10 temperature at package edge
and
and
+ T
9,10A
+ T
P4
9,10A
o
= 314 mW, T
values shown here are for PCB layouts shown in Figure 78 with
P9,10
are
A
30
If we, however, assume a worst
case PCB layout and no air flow
where the estimated
junction temperatures become
T
T
The output IC junction
temperature exceeds the absolute
maximum specification of 125 C.
In this case, PCB layout and
airflow will need to be designed
so that the junction temperature
of the output IC does not exceed
125 C.
If the calculated junction
temperatures for the thermal
model in Figure 78 is higher than
125 C, the pin temperature for
pins 9 and 10 should be
measured (at the package edge)
under worst case operating
environment for a more accurate
estimate of the junction
temperatures.
9,10A
ji
jo
+ 100 C/W) + 100 C = 115 C
+ 100 C/W) + 100 C = 131 C
= (90.8 mW)(60 C/W
= (240 mW)(30 C/W
are 100 C/W. Then the
4A
and