74LS645 Octal Bus Transceiver Tri-State
Package SOIC-20, PDIP-20, SO-20 Series 74LS Status Active (7-Oct-2021)
74LS645 overview
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. 74LS645 octal bus transceivers are designed for asynchronous two-way communication between data buses. The devices transmit data from the A bus to the B bus or from the B bus to the A bus depending upon the level at the direction control (DIR) input.
Key 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
Datasheet
sn74ls645.pdf
74LS645 features
- Designed for Asynchronous two-way Communication between Data Buses
- Hysteresis at Bus Inputs Improves Noise Margins
- 3-State Outputs Drive Bus Lines Directly
- Operating Temperature up to 70°C
- Standard TTL Switching Voltages
74LS645 pinout
| Pin | Name | Description |
|---|---|---|
| 1 | DIR | Direction Control Pin |
| 2 | A1 | Input/Output of Bus Transceiver A |
| 3 | A2 | Input/Output of Bus Transceiver A |
| 4 | A3 | Input/Output of Bus Transceiver A |
| 5 | A4 | Input/Output of Bus Transceiver A |
| 6 | A5 | Input/Output of Bus Transceiver A |
| 7 | A6 | Input/Output of Bus Transceiver A |
| 8 | A7 | Input/Output of Bus Transceiver A |
| 9 | A8 | Input/Output of Bus Transceiver A |
| 10 | GND | Ground |
| 11 | B8 | Input/Output of Bus Transceiver B |
| 12 | B7 | Input/Output of Bus Transceiver B |
| 13 | B6 | Input/Output of Bus Transceiver B |
| 14 | B5 | Input/Output of Bus Transceiver B |
| 15 | B4 | Input/Output of Bus Transceiver B |
| 16 | B3 | Input/Output of Bus Transceiver B |
| 17 | B2 | Input/Output of Bus Transceiver B |
| 18 | B1 | Input/Output of Bus Transceiver B |
| 19 | G' | Enable Pin |
| 20 | VCC | Positive Supply |
74LS645 applications
- transmit the data in the form of voice or data or video over the wireless medium
More about 74LS645
74LS645 Alternative Equivalent
74LS640
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