9.3 Thermal Derating

Temperature rise increases with frequency, load current, input voltage and smaller board dimensions. On a typical board, the LMR24220 is capable of supplying 2 A below an ambient temperature of 50°C under worst case operation with input voltage of 42 V. Figure 27 shows a thermal derating curve for the output current without thermal shutdown against ambient temperature up to 125°C. Obtaining 2-A output current is possible at higher temperature by increasing the PCB ground plane area, adding air flow or reducing the input voltage or operating frequency

θ_JA = 40°C/W, V_OUT = 3.3 V, ƒ_SW = 500 kHz
(tested on the evaluation board)

Figure 27. Thermal Derating Curve