The design in this example is trying to achieve 1000 μs rise time for power sequencing, with both V_BIAS and V_IN to be 5 V. From Table 8-1, the I_ON needs to be between 20 μA and 100 μA. To find the I_ON needed to achieve 1000 μs rise time, linear interpolation can be used to estimate as below:

where:

• T_R is the desired T_R, which is 1000 μs
• I_ON is the desired I_ON
• T_R1 is the first T_R used for linear interpolation, which is 2580 μs
• T_R2 is the second T_R used for linear interpolation, which is 688 μs
• I_ON1 is the first I_ON used for linear interpolation, which is 20 μA
• I_ON2 is the second I_ON used for linear interpolation, which is 100 μA

I_ON is calculated to be 86.8 μA. To find the R_T value, plug in the parameters in Equation 1.

R_T = 1000 × (5 V − 1.2 V) / 86.8 μA − 11.5 kΩ = 32.2 kΩ

By using the standard resistor value closest to 32.2 kΩ, the typical rise time can be calculated for the actual resistor value used on board.