(1) The maximum safety temperature, T
S, has the same value as the maximum junction temperature, T
J, specified for the device. The I
S and P
S parameters represent the safety current and safety power respectively. The maximum limits of I
S and P
S should not be exceeded. These limits vary with the ambient temperature, T
A. The junction-to-air thermal resistance, R
θJA, in the
Thermal Information table is that of a device installed on a high-K test board for leaded surface-mount packages. Use these equations to calculate the value for each parameter: T
J = T
A + R
θJA × P, where P is the power dissipated in the device. T
J(max) = T
S = T
A + R
θJA × P
S, where T
J(max) is the maximum allowed junction temperature. P
S = I
S × V
I, where V
I is the maximum input voltage.