Calculating the case temperature (Tc) of MOSFET and controller in CCG7DC – KBA236784

[Infineon_Team]

To calculate the device's maximum case temperature, use the following formula:

T_case-max = T_junction-max-(θ_{junction-to-case}×P_dissipated)

Where,

• T_case-max : Maximum case temperature
• T_junction-max : Maximum junction temperature
• θ_{junction-to-case} : Thermal resistance of junction to case
• P_dissipated : Power dissipation

Case1: Case temperature (Tc) of CCG7DC controller

1. The operating temperature of the CCG7DC is between -40℃ and 105℃.
2. If extended till 125℃, it may shorten the useful life of the device.
3. Usage above the absolute maximum conditions, i.e., above 125℃ may cause permanent damage to the device.

The CCG7DC thermal resistance of the case is 12.9℃/W. See Figure 1 for datasheet reference.

 Figure 1 Example datasheet

In Figure 1, T_case-max = T_junction-max -12.9*PD
–40℃ <T_j  < 125℃

Case 2: Case temperature (Tc) of MOSFET

BSZ063N04LS6 is considered for analysis since it is used in the 45W USB-PD Dual C Power Adapter Solution with PAG1P-A3/PAG1S-A1+CCG7D-C controllers.

 The operating temperature of the MOSFET is between -55℃ and 175 ℃.

The MOSFET thermal resistance of the case is 4℃/W. See Figure 2 for datasheet reference.

Figure 2 Example datasheet

In Figure 2, T_case-max = T_junction-max -4*PD
–55℃ <T_j  < 175℃

Note: Higher the Power Dissipation (Pd), lower the maximum case temperature.

Example: Tc of MOSFET

Considering that T_j   is 125℃ and 20W of power is dissipated, the case temperature under the given conditions is as follows:

T_case-max = T_junction-max -4*PD
                     = 125 – 4*20
                     = 45℃