ZHCSBB4B July 2013 – June 2017 TPS61197
PRODUCTION DATA.
R5 determines the correct overcurrent limit protection. To choose the right value of R5, start with the total system power needed POUT, and calculate the input current IIN by Equation 6. Efficiency can be estimated from Figure 20. The second step is to calculate the inductor peak current based on the inductor value L using Equation 7 and Equation 8. The maximum R5 can now be calculated as R5(maximum) = VISNS_OC / IL(P). TI recommends adding 20% or more margins to account for component variations. A small filter placed on the ISNS pin improves performance of the converter (see R6 and C5 in Figure 18). The time constant of this filter must be approximately 100 ns. The range of R6 must be from about 300 Ω to 1 kΩ for best results. Locate C5 as close as possible to the ISNS pin to provide noise immunity.