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4. Estimation of Junction Temperature (Tj)
4 Estimation of Junction Temperature (Tj)
• Junction temperature (Tj) could be estimated by the equation below in Figure 11.
• Tc point can be measured as described in Figure 10.
Fixture or Heat sink
Thermal Pad
Figure8. Temperature of the Module at each position
• How to obtain the value of Tj when Tc is measured at 50℃
※ Basic Equation → Tj = Tc + Ptotal x Rjc
- Ptotal = Typical Input Current x Forward Voltage = 0 5[A] x 24 0[V] = 12 0[W]
Ptotal Typical Input Current x Forward Voltage
- Rjc = 1.6 [℃/W] → The value of Thermal Resistance is obtained by LGIT internal
experiment
ex) Tj = Tc + Rjc x Ptotal = 50[℃] + 1.6[℃ /W] x 12[W] = 69.2[℃]
T
j
- 19 -
T
c
R
jc
T
= T
+ P
x R
j
c
total
0.5[A] x 24.0[V]
(Tj ~ Tc)
jc
12.0[W]
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