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AV02-2947EN - September 23, 2013
Thermal Model for ACPL-P484/W484
SO6 Package Optocoupler
Denitions
R
11
: Junction to Ambient Thermal Resistance of LED due
to heating of LED
R
12
: Junction to Ambient Thermal Resistance of LED due
to heating of Detector (Output IC)
R
21
: Junction to Ambient Thermal Resistance of Detector
(Output IC) due to heating of LED.
R
22
: Junction to Ambient Thermal Resistance of Detector
(Output IC) due to heating of Detector (Output IC).
P
1
: Power dissipation of LED (W).
P
2
: Power dissipation of Detector / Output IC (W).
T
1
: Junction temperature of LED (˚C).
T
2
: Junction temperature of Detector (˚C).
T
a
: Ambient temperature.
∆T
1
: Temperature dierence between LED junction and
ambient (˚C).
∆T
2
: Temperature deference between Detector junction
and ambient.
Ambient Temperature: Junction to Ambient Thermal Re-
sistances were measured approximately 1.25cm above
optocoupler at ~23˚C in still air
Description
This thermal model assumes that an 6-pin single-channel
plastic package optocoupler is soldered into a 7.62 cm x
7.62 cm printed circuit board (PCB). The temperature at
the LED and Detector junctions of the optocoupler can be
calculated using the equations below.
T
1
= (R
11
* P
1
+ R
12
* P
2
) + T
a
-- (1)
T
2
= (R
21
* P
1
+ R
22
* P
2
) + T
a
-- (2)
Jedec Specications R
11
R
12
, R
21
R
22
low K board
167 64, 81 89
high K board
117 31, 39 54
Notes:
1. Maximum junction temperature for above parts: 125 °C.
Thermal Model for ACPL-M484
SO5 Package Optocoupler
Denitions
R
11
: Junction to Ambient Thermal Resistance of LED due
to heating of LED
R
12
: Junction to Ambient Thermal Resistance of LED due
to heating of Detector (Output IC)
R
21
: Junction to Ambient Thermal Resistance of Detector
(Output IC) due to heating of LED.
R
22
: Junction to Ambient Thermal Resistance of Detector
(Output IC) due to heating of Detector (Output IC).
P
1
: Power dissipation of LED (W).
P
2
: Power dissipation of Detector / Output IC (W).
T
1
: Junction temperature of LED (˚C).
T
2
: Junction temperature of Detector (˚C).
T
a
: Ambient temperature.
∆T
1
: Temperature dierence between LED junction and
ambient (˚C).
∆T
2
: Temperature deference between Detector junction
and ambient.
Ambient Temperature: Junction to Ambient Thermal Re-
sistances were measured approximately 1.25cm above
optocoupler at ~23˚C in still air
Description
This thermal model assumes that an 5-pin single-channel
plastic package optocoupler is soldered into a 7.62 cm x
7.62 cm printed circuit board (PCB). The temperature at
the LED and Detector junctions of the optocoupler can be
calculated using the equations below.
T
1
= (R
11
* P
1
+ R
12
* P
2
) + T
a
-- (1)
T
2
= (R
21
* P
1
+ R
22
* P
2
) + T
a
-- (2)
Jedec Specications R
11
R
12
, R
21
R
22
low K board
191 77, 91 99
high K board
126 26, 35 51
Notes:
1. Maximum junction temperature for above parts: 125 °C.