74191

• Logic Family: TTL (74xx series)
• Function: 4-bit synchronous up/down binary counter
• Package: 16-pin DIP
• Count Range: 0 to 15 (binary)
• Clock Input: Synchronous clock
• Count Direction Control: Up/Down input
• Parallel Data Inputs: 4 (A–D)
• Parallel Load: Active LOW load input
• Outputs: Q0–Q3
• Terminal Count Outputs:
  
  • Ripple Carry (RC)
  • Terminal Count (TC) for cascading
• Enable Inputs: Count enable/control inputs
• Supply Voltage (Vcc): 4.75 V – 5.25 V (5 V nominal)
• Absolute Max Vcc: ~7 V
• Input Voltage Range: –0.5 V to Vcc
• Logic HIGH (VIH): ≥ 2.0 V
• Logic LOW (VIL): ≤ 0.8 V
• Output HIGH (VOH): ≥ 2.4 V
• Output LOW (VOL): ≤ 0.4 V
• Propagation Delay: ~20–35 ns typical
• Max Clock Frequency: ~25 MHz (typical TTL conditions)
• Power Dissipation: ~60 mW typical
• Operating Temperature: 0 °C to 70 °C

• Synchronous up/down counting
• Parallel preset capability
• Cascade connection for larger counters
• High-speed TTL operation
• Terminal count outputs for expansion

Typical Applications

• Digital counters
• Frequency division
• Position counting
• Timers
• Control systems and sequencing