SLVAFY4 January   2025 TPS543B25T

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Understanding Thermals
  5. 2Methods of Heat Dissipation
    1. 2.1 Routable Lead Frame
  6. 3Thermally Enhanced Package
  7. 4SOA Comparison
  8. 5Conclusions

4 SOA Comparison

Lower junction temperatures across load widens the SOA of a given device, enabling higher current output in high ambient temperatures.

Figure 4-1 shows the SOA curve of the TPS543B25 buck converter vs the SOA curve of TPS543B25T.

SOA Curve, TPS543B25T vs TPS543B25 Figure 4-1 SOA Curve, TPS543B25T vs TPS543B25

Standard package TPS543B25 would not be able to output full load at TA above 70°C. A heat sink applied to the over-molded package also yields very little benefits. TPS543B25T with a heat sink can safely output full load at up to 83°C TA, and up to 105°C TA with airflow added.

Since the TEP benefits in SOA and junction temperature increase with output current, we can also extrapolate this data to infer that TEP will be even more beneficial in higher current (>25A) devices, especially in higher ambient temperature (85°C+ environments).

Note that there were no significant differences between the SOA of TPS543B25 and TPS543B25T when there is no heat sink used. The exposed silicon die is only able to conduct heat to ambient through a heat sink. There were also no significant differences found between the SOA of the standard package with heat sink and without heat sink, confirming that the top side mold compound prevents heat dissipation.