The underlying thermal limitation of the DLPC23xS-Q1 is that the maximum operating junction temperature (T_J) not be exceeded (this is defined in Section 5.3). This temperature is dependent on operating ambient temperature, airflow, PCB design (including the component layout density and the amount of copper used), power dissipation of the DLPC23xS-Q1, and power dissipation of surrounding components. The DLPC23xS-Q1’s package is designed primarily to extract heat through the power and ground planes of the PCB. Thus, copper content and airflow over the PCB are important factors.

TI highly recommends that after the host PCB is designed and built that the thermal performance be measured and validated.

To do this, measure the top center case temperature under the worse case product scenario (max power dissipation, max voltage, max ambient temperature) and validate that the maximum recommended case temperature (T_C) is not exceeded. This specification is based on the measured φ_JT for the DLPC23xS-Q1 package and provides a relatively accurate correlation to junction temperature. Take care when measuring this case temperature to prevent accidental cooling of the package surface. TI recommends a small (approximately 40 gauge) thermocouple. The bead and thermocouple wire must contact the top of the package and be covered with a minimal amount of thermally conductive epoxy. The wires must be routed closely along the package and the board surface to avoid cooling the bead through the wires.