SBOS153B September 2000 – January 2016 OPA541
Figure 18 provides the recommended solder footprint for the TO-220 power package. The tab is electrically connected to the negative supply, V–. It may be desirable to isolate the tab of the TO-220 package from its mounting surface with a mica (or other film) insulator. For lowest overall thermal resistance, it is best to isolate the entire heat sink or OPA541 structure from the mounting surface rather than to use an insulator between the semiconductor and heat sink.