by Equation 28: peak current into the switches is around 400 mA and the TJ Tamb maximum allowable R DS(on)for the MOSFET is given by Pmax + (28) Equation 29: Rth j R DS(on)(max) + P (29) Under the above conditionsJ T = (150−60)/150 = 600 mW DRMS 2 2 This value yields a zero safety margin because it assumes In this example, DS(on) = 0.2/((0.4/√2) ) = 2.50 Ω. the die is continuously operating at its maximum Obviously, this is the maximum value at T J +120°C, temperature. The transistor lifetime is highly reduced as a yielding
