The power handling capability of the device is limited by the maximum rated junction temperature (125°C). The power dissipated by the device is made up of two components:

1. Output current multiplied by the input and output voltage differential: I_OUT(V_IN – V_OUT).
2. GND pin current multiplied by the input voltage: I_GNDV_IN.

The GND pin current can be found using the GND Pin Current graphs in Typical Characteristics. Power dissipation is equal to the sum of the two components listed above.

The TL1963A-Q1 series regulators have internal thermal limiting designed to protect the device during overload conditions. For continuous normal conditions, the maximum junction temperature rating of 125°C must not be exceeded. It is important to carefully consider all sources of thermal resistance from junction to ambient. Additional heat sources mounted nearby must also be considered.

For surface-mount devices, heat sinking is accomplished by using the heat-spreading capabilities of the PCB and its copper traces. Copper board stiffeners and plated through-holes also can be used to spread the heat generated by power devices.

Table 4 lists thermal resistance for several different board sizes and copper areas. All measurements were taken in still air on 1/16-inch FR-4 board with one-ounce copper.