8.2.4.7 Noisy Input Line Condition

A small, low-pass RC filter should be used at the input pin of the LM2585 if the input voltage has an unusual large amount of transient noise, such as with an input switch that bounces. The circuit in Figure 44 demonstrates the layout of the filter, with the capacitor placed from the input pin to ground and the resistor placed between the input supply and the input pin. Note that the values of R_IN and C_IN shown in the schematic are good enough for most applications, but some readjusting might be required for a particular application. If efficiency is a major concern, replace the resistor with a small inductor (say 10 μH and rated at 100 mA).