A decade counter is a type of digital counter circuit that counts in decimal (base-10) representation. It is specifically designed to count pulses or clock signals and produce a binary-coded decimal (BCD) output. Each time it receives a clock pulse, it advances its count by one, following a sequence from 0 to 9 before resetting to 0 and starting over. This makes it suitable for applications where you need to count events or occurrences up to ten.
Here's a basic explanation of how a decade counter counts pulses:
Clock Input (Pulses): The decade counter has an input pin for receiving clock pulses. A clock pulse is a short burst of electrical signal that occurs at a regular interval. Each time a clock pulse is received at the input, the counter advances its count by one.
Counting Sequence: The decade counter follows a specific sequence as it counts the clock pulses. It starts from 0 and goes up to 9 in binary-coded decimal (BCD) representation. The BCD representation uses four bits to represent each decimal digit, which means that the counter's output will have four output pins for each digit.
Output Pins: The output pins of the decade counter provide the BCD representation of the current count. For example, if the counter is at count 5, the output pins might show the binary value 0101, which corresponds to the decimal digit 5.
Reset: When the counter reaches the count of 9, the next clock pulse will cause it to reset back to 0. This ensures that the counter stays within the range of 0 to 9, just like a decade (10 years) cycles back to 0 after reaching 9.
Decade counters can be constructed using various digital logic components such as flip-flops, gates, and other combinational logic elements. Integrated circuits (ICs) designed specifically for decade counting, like the 74LS90, are readily available and make it easier to implement this functionality.
Applications of decade counters include digital frequency dividers, event counters, digital clocks, and other systems where you need to track or display events or time intervals in decimal format.