76. LED Electrical Characteristics

You’re using a SMD LED.

Consider-

• Typical forward voltage VF​≈3.2V at 20 mA.
• Thermal resistance (junction-to-ambient, RθJA) ≈ 200 °C/W.
• Max junction temperature = 125 °C.

Scenario: The LED runs at I_F = 20 mA, ambient = 40 °C.

What will be the approximate junction temperature (Tj)?