We can construct a tachometer using the TC9400 in the F/V mode to convert the frequency information (RPM) into a linearly proportional voltage. Then we can compare this voltage to one of “n” comparators (on this example using 8). The respective LED lights up and will continue to stay lit as long as the voltage exceeds the trip point when he voltage exceed the trip point of comparator. This will give us a bar-graph-type display. The height of this bar is proportional to RPM.
[Circuit’s schematic diagram source: Microchip’s Application Note]