MC10137

The MC10137 is a high speed synchronous counter that can count up, down, preset, or stop count at frequencies exceeding 100 MHz. The flexibility of this device allows the designer to use one basic counter for most applications. The synchronous count feature makes the MC10137 suitable for either computers or instrumentation.

Three control lines (S1, S2, and Carry In) determine the operation mode of the counter. Lines S1 and S2 determine one of four operations; preset (program), increment (count up), decrement (count down), or hold (stop count). Note that in the preset mode a clock pulse is necessary to load the counter, and the information present on the data inputs (D0, D1, D2, and D3) will be entered into the counter. Carry Out goes low on the terminal count. The Carry Out on the MC10137 is partially decoded from Q1 and Q2 directly, so in the preset mode the condition of the Carry Out after the Clock's positive excursion will depend on the condition of Q1 and/or Q2. The counter changes state only on the positive going edge of the clock. Any other input of MC10137 may change at any time except during the positive transition of the clock. The sequence for counting out of improper states is as shown in the State Diagrams.