Odd-frequency counter with symmetrical output waveform (SN7474, SN74163)

As shown in the figure, it is an odd-frequency division counting circuit with symmetrical output waveform. Sometimes it is necessary to divide the clock pulse into odd frequencies, and the output is required to have a 50% duty cycle. In this case, adding two triggers and several gate circuits to a general counter can meet the above requirements, as shown in the figure. When the 20-bit output of the counter is logic "1", and the 21st and 22nd bit outputs are logic "0", point B is logic "0"; when the 22-bit output of the counter is logic "1", point A is logic "0". Therefore, the output frequency of the NOR gate G1 is 2MHz. Finally, the symmetrical square wave of 1MHz is output by dividing by two, and the requirement of 5-frequency division is met.