The ZL40815 is one of a range of 5V supply, very high speed, low power prescalers for professional applications with a fixed modulus of divide by 4. The dividing elements are static D type flip flops, and therefore, allow operation down to DC if the drive signal is a pulse waveform with fast risetimes. The output stage has internal 50 ohm pull up giving a 1V p-p output. See application notes for more details