hcpl-788j-560e Avago Technologies, hcpl-788j-560e Datasheet - Page 17

• Manufacturer Part Number: hcpl-788j-560e
• Description: Very High Cmr 2.5 Amp Output Current Igbt Gate Driver Optocoupler
• Manufacturer: Avago Technologies

Thermal Model
(Discussion applies to ACPL-3130, ACPL-J313 and ACNW3130)
The steady state thermal model for the ACPL-3130 is
shown in Figure 32. The thermal resistance values given
in this model can be used to calculate the temperatures
at each node for a given operating condition. As shown
by the model, all heat generated flows through q
raises the case temperature T
q
therefore, determined by the designer. The value of q
83°C/W was obtained from thermal measurements using a
2.5 x 2.5 inch PC board, with small traces (no ground plane),
a single ACPL-3130 soldered into the center of the board
and still air. The absolute maximum power dissipation
derating specifications assume a q
From the thermal mode in Figure 32 the LED and detector
IC junction temperatures can be expressed as:

Figure 32. Thermal Model.
T
T
T
T
T
package bottom
q
q
q
q
*q
of the part.
θ
LC
JE
JD
JE
JD
C
CA
LC
LD
DC
CA
= case temperature measured at the center of the
CA
= LED junction temperature
= detector IC junction temperature
=
=
= LED-to-case thermal resistance
= 467 °C/W
depends on the conditions of the board design and is,
= LED-to-detector thermal resistance
= case-to-ambient thermal resistance
= detector-to-case thermal resistance
will depend on the board design and the placement
P
P
E
E
•
•
T
(
(
θ
JE
LC
θ
θ
LC
||
LD
θ
(
+
θ
LC
= 442 °C/W
LD
θ
•
DC
T
+
θ
C
+
θ
DC
θ
DC
θ
CA
T
LD
A
)
+
= 83 °C/W*
+
θ
T
DC
θ
θ
JD
CA
CA
)
= 126 °C/W
)
+
+
P
P
C
D
D
•
accordingly. The value of
•
(
(
θ
θ
CA
LC
DC
θ
value of 83°C/W.
+
||
LC
θ
(
θ
•
DC
LD
θ
DC
+
+
θ
θ
LD
LC
)
+
+
θ
θ
CA
CA
CA
)
which
)
+
+
CA
T
T
A
A
=
Inserting the values for q
gives:
For example, given P
and q
T
board layout and part placement (q
application
T
T
T
T
JE
JD
JE
JE
JD
and T
=
=
=
=
=
=
P
P
P
P
45mW
45
CA
E
E
E
E
•
•
•
•
mW
= 83°C/W:
(
(
140
339
256
57
JD
°
•
•
°
°
C/W
should be limited to 125°C based on the
°
339
140
C/W
C/W
C/W
°
°
+
C/W
C/W
+
+
+
θ
P
θ
P
CA
D
CA
D
•
)
+
•
+
E
)
140
+
= 45 mW, P
194
+
250
250
P
P
D
°
D
•
C/W
°
LC
mW
mW
C/W
•
(
111
and q
(
57
•
•
+
+
°
140
194
°
C/W
T
C/W
T
A
A
°
°
O
DC
C/W
C/W
= 250 mW, T
+
+
shown in Figure 32
θ
θ
CA
CA
CA
+
+
)
)
) specific to the
70
70
+
+
T
T
°
°
C
A
A
C
=
120
A
= 70°C
°
C