The DACx750 is designed for a maximum junction temperature of 150°C. In cases where the maximum AVDD is driving maximum current into ground, this junction temperature can be exceeded. Use Equation 7 to determine the maximum junction temperature that can be reached.

where

• T_J max = 150°C
• T_A is the ambient temperature
• θ_JA is the package-dependent, junction-to-ambient thermal resistance, found in Section 7.4.

The power dissipation is calculated by multiplying all the supply voltages with the currents supplied, which are found in the Power Requirements subsection of Section 7.5.

Consider an example: IOUT is enabled, supplying 24 mA into GND with a 25°C ambient temperature, AVDD of 24 V, and DVDD is generated internally. From the Section 7.5, the max value of AIDD = 3 mA when IOUT is enabled and DAC code = 0x0000. Also, the max value of DIDD = 1 mA. Accordingly, the worst-case power dissipation is 24 V × (24 mA + 3 mA + 1 mA) = 672 mW. Using the θ_JA value for the TSSOP package, we get T_J max = 25°C + (32.3 × 0.672)°C = 46.7°C. At 85°C ambient temperature, the corresponding value of T_J max is 106.7°C. Using this type of analysis, the system designer can both specify and design for the equipment operating conditions. Note that for enhanced thermal performance, connect the thermal pad in both packages to a copper plane.