The 74LS series of integrated circuits (ICs) was one of the most popular logic families of transistor-transistor logic (TTL) logic chips. 74LS series is a bipolar, low-power Schottky IC. The 74LS191 is synchronous, reversible up/down counters having a complexity of 58 equivalent gates.
74LS191 Features
- Synchronous Up/Down Mudulo-16 Binary Counter, Count is Updated with Low-to-High Clock Transition
- Synchronous Counting
- High Speed up to 25MHz
- Individual Preset Inputs
- Standard TTL Switching Voltages
74LS191 Specifications
| Supply Voltage | 4.75 – 5.25Vdc |
| Maximum Clock Frequency | 40Mhz |
| Power Dissipation | 2mW/gate @100kHz |
| Minimum Output Current | 8mA |
| Propagation Delay | 10nS |
| Fan Out (TTL Loads) | 20 |
74LS191 Pinout Diagram
74LS191 Pin Description
| Pin No | Pin Name | Description |
| 1 | B | Data Input Of Counter B |
| 2 | QB | Output Of Counter QB |
| 3 | QA | Output Of Counter QA |
| 4 | CTEN’ | Clock Enable |
| 5 | D/U’ | Down/Up(Active Low) |
| 6 | QC | Output Of Counter QC |
| 7 | QD | Output Of Counter QD |
| 8 | GND | Ground |
| 9 | D | Data Input Of Counter D |
| 10 | C | Data Input Of Counter V |
| 11 | LOAD’ | Load Pin(Active Low) |
| 12 | MAX/MIN | Maximum/Minimum |
| 13 | RCO’ | Ripple Carry Output(Active Low) |
| 14 | CLK | Clock Pin |
| 15 | A | Data Input Of Counter A |
| 16 | VCC | Positive Supply |
Applications
- Frequency counters
- Digital clocks
- Analog to digital converters
- With some changes in their design, counters can be used as frequency divider circuits
- In time measurement
74LS191 Alternative Equivalent
Download the 74LS191 Up/Down Binary Counter Datasheet from the link given below.
