74161 IC Synchronous 4-Bit Binary Counter
The IC 74161 is a synchronous 4-bit binary counter designed to count from 0000 (0) to 1111 (15). It updates all flip-flop outputs simultaneously on the clock’s active edge, preventing glitches common in ripple counters.
It provides an asynchronous clear (CLR) input that forces all outputs LOW regardless of the clock. A parallel load (LOAD) function allows presetting a specific starting count. The IC includes two enable inputs (ENP, ENT) for count control and a terminal count (TC) output that indicates when the maximum count (15) is reached, allowing for cascading multiple counters to build wider counting ranges.
The 74161 integrates easily into frequency dividers, event counters, and timing circuits. Its TTL compatibility and synchronous design make it reliable for high-speed digital applications.
Pin Configuration (DIP-16)
| Pin | Name | Description |
|---|---|---|
| 1 | CLR | Asynchronous Clear (active LOW) |
| 2 | CLK | Clock Input |
| 3 | D | Parallel Data Input (MSB) |
| 4 | C | Parallel Data Input |
| 5 | B | Parallel Data Input |
| 6 | A | Parallel Data Input (LSB) |
| 7 | QA | Output Bit 0 |
| 8 | GND | Ground |
| 9 | QB | Output Bit 1 |
| 10 | QC | Output Bit 2 |
| 11 | QD | Output Bit 3 (MSB) |
| 12 | TC | Terminal Count Output |
| 13 | ENT | Count Enable (T) |
| 14 | ENP | Count Enable (P) |
| 15 | LOAD | Parallel Load (active LOW) |
| 16 | VCC | +5V Power Supply |
Key Features
Synchronous 4-bit binary counting (0–15)
Asynchronous clear and parallel load
Terminal count output for cascading
TTL-compatible logic
Supports high-speed counting
Compact DIP-16 or SOIC-16 package
Applications
Count up to 16 pulses in control circuits.
Divide input clock signals by 16.
Build multi-bit counters using cascading.
Create event counters in automation systems.
Use as a programmable counter with preset inputs.
Drive timing sequences in digital controllers.
Design frequency counters for measurement systems.
Generate pulses for display multiplexing.
Control sequence logic in digital devices.
Implement counter-based lab experiments.
Specifications Table
| Parameter | Value |
|---|---|
| Logic Family | TTL |
| Function | Synchronous Binary Counter |
| Count Range | 0–15 (mod-16) |
| Inputs | Clock, CLR, LOAD, ENP, ENT |
| Outputs | Q0–Q3, TC |
| Input HIGH Voltage | ≥ 2.0V |
| Input LOW Voltage | ≤ 0.8V |
| Output HIGH Voltage | ≥ 2.4V |
| Output LOW Voltage | ≤ 0.4V |
| Propagation Delay | ~25 ns |
| Max Clock Frequency | ~35 MHz |
| Supply Voltage (Vcc) | 4.75V to 5.25V |
| Operating Temp | 0°C to 70°C ‘ |
| Package Type | DIP-16 / SOIC-16 |
| Number of Pins | 16 |
