A binary coded decimal (BCD) Up/Down Counter consisting of four synchronously clocked D-type flip-flops connected as a counter. It can either count up from zero to nine or down from nine to zero. The output is indicated in binary. Supplied in a 16 pin DIL package.
Pin Out information:
The diagram below shows how the counter operates when clocked, the solid line indicates a clock when set to count up and the dotted line when set to count down. The second number in each of the boxes is the binary representation of the data that will be present on the counter outputs Q3 to Q0.
In addition to the four outputs Q3 to Q0, there are four inputs P3 to P0 to Parallel Load (PL) a desired value. When the PL pin is taken high the data on the inputs P3 to P0 are loaded into the counter. This functionality can be used to reload the counter with any value.
The following table lists the pins not mentioned so far and their setting:
| Pin Name | Input/Output. | Description. |
|---|---|---|
| CE | Input | Count enable (active low) Low = Counting functionality enabled High = Clocking the count line has no effect, the previous value is held |
| CP | Input | Clock pulse – causes the count to either go up or down by one, clocking take place on the rising edge |
| UP/DN | Input | Up / Down mode Low = down High = up |
| MR | Input | Master Reset (active high) Low = normal operation High = hold the device in a reset state, where CP, PL and outputs Q3 to Q0 are disabled. The count is zeroed. |
| TC | Output | Terminal Count (active low) Low = the count is about to wrap around High = normal operation. The terminal count pin can be used to clock a 2nd counter. TC is low when the count is zero for down counting, or low when the count is nine for up counting. Thus as the count actually wraps around the TC pin changes from low to high, which can be fed into the CP of the next digit. |
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