In most cases, a small filter placed on the ISNS pin improves performance of the converter. These are the components RIFLT and CIFLT in Figure 26. The time constant of this filter should be approximately 10% of the nominal pulse width of the converter. The pulse width can be found using Equation 20.
The suggested time constant is then
The range of RIFLT should be from about 1 kΩ to 5 kΩ for best results. Higher values can be used but this raises the impedance of the ISNS pin connection more than necessary and can lead to noise pickup issues in some layouts. CIFLT should be located as close as possible to the ISNS pin as well to provide noise immunity.