Rechteck-Oszillator (mit OpAmp)

A new Mostek IC, the MK 5009, is a complete timebase for frequency counters and other applications. The internal block diagram of the IC is shown in figure 1. It incorporates a clock circuit (which may be used either with an external reference frequency, with an external RC circuit or with an external crystal) and a programmable divider. By applying an appropriate binary code to the programming inputs the division ratio may be varied in decade `teps from 1 o 0 to I 08• Other division ratios are also available, the most interesting being divide-by-2 x 104, which gives a 50 Hz output with a 1 MHz clock frequency or a 60 Hz output with a I .2 MHz clock frequency.