The useful range of a driver is greatly affected by the drive power requirements of the load and the thermal characteristics of the package. For a power driver to be useful over a particular temperature range, the package must allow for the efficient removal of the heat produced while keeping the junction temperature within rated limits. The UCC27324-Q1 device of drivers is available in three different packages to cover a range of application requirements.

As shown in Section 5.4, the SOIC-8 (D) package has power ratings of approximately 0.5 W at T_A = 70°C. This limit is imposed in conjunction with the power derating factor also given in the table. Note that the power dissipation in our earlier example is 0.432 W with a 10-nF load, 12-V V_DD, switched at 300 kHz. Thus, only one load of this size could be driven using the D or P package, even if the two onboard drivers are paralleled. The difficulties with heat removal limit the drive available in the older packages.