Broadcom

ACPL-K43CT-K44CT-DS100

14

ACPL-K43CT, ACPL-K44CT Data Sheet

Automotive R2Coupler™ Wide Operating Temperature 1-MBd Digital Optocoupler in a

Stretched 8-Pin Surface-Mount Plastic Package

Thermal Resistance Model for ACPL-K44CT

The diagram of ACPL-K44CT for measurement is shown in Figure 18. Here, one die is heated first and the temperatures of

all the dice are recorded after thermal equilibrium is reached. Then, the second, third, and fourth die are heated and all the

dice temperatures are recorded. With the known ambient temperature, the die junction temperature and power dissipation,

the thermal resistance can be calculated. The thermal resistance calculation can be cast in matrix form. This yields a 4 by 4

matrix for the case of two heat sources.

Figure 18: Diagram of ACPL-K44CT for Measurement

R11

R12

R13

R14

×

P1

=

ΔT1

R21

R22

R23

R24

P2

ΔT2

R31

R32

R33

R34

P3

ΔT3

R41

R42

R43

R44

P4

ΔT4

R11

: Thermal Resistance of Die1 due to heating of Die1 (°C/W)

R12

: Thermal Resistance of Die1 due to heating of Die2 (°C/W)

R13

: Thermal Resistance of Die1 due to heating of Die3 (°C/W)

R14

: Thermal Resistance of Die1 due to heating of Die4 (°C/W)

R21

: Thermal Resistance of Die2 due to heating of Die1 (°C/W)

R22

: Thermal Resistance of Die2 due to heating of Die2 (°C/W)

R23

: Thermal Resistance of Die2 due to heating of Die3 (°C/W)

R24

: Thermal Resistance of Die2 due to heating of Die4 (°C/W)

R31

: Thermal Resistance of Die3 due to heating of Die1 (°C/W)

R32

: Thermal Resistance of Die3 due to heating of Die2 (°C/W)

R33

: Thermal Resistance of Die3 due to heating of Die3 (°C/W)

R34

: Thermal Resistance of Die3 due to heating of Die4 (°C/W)

R41

: Thermal Resistance of Die4 due to heating of Die1 (°C/W)

R42

: Thermal Resistance of Die4 due to heating of Die2 (°C/W)

R43

: Thermal Resistance of Die4 due to heating of Die3 (°C/W)

R44

: Thermal Resistance of Die4 due to heating of Die4 (°C/W)

P1

: Power dissipation of Die1 (W)

P2

: Power dissipation of Die2 (W)

P3

: Power dissipation of Die3 (W)

P4

: Power dissipation of Die4 (W)