These 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. The enable input (G) can be used to disable the device so the buses are effectively isolated.
The -1 versions of the SN74LS640 thru SN74LS642, SN74LS644, and SN74LS645 are identical to the standard versions except that the recommended maximum IOL is increased to 48 milliamperes. There are no -1 versions of the SN54LS640 thru SN54LS642, SN54LS644, and SN54LS645.
The SN54LS640 thru SN54LS642, SN54LS644, and SN54LS645 are characterized for operation over the full military tempearture range of 55°C to 125°C. The SN74LS640 thru SN74LS642, SN74LS644, and SN74LS645 are characterized for operation from 0°C to 70°C.
| Supply voltage (min) (V) | 4.75 |
| Supply voltage (max) (V) | 5.25 |
| Number of channels | 8 |
| IOL (max) (mA) | 24 |
| IOH (max) (mA) | 0.1 |
| Input type | TTL |
| Output type | TTL |
| Features | High speed (tpd 10-50ns) |
| Technology family | LS |
| Rating | Catalog |
| Operating temperature range (°C) | 0 to 70 |
| PDIP (N) | 20 | 228.702 mm² 24.33 x 9.4 |
| SOIC (DW) | 20 | 131.84 mm² 12.8 x 10.3 |
| SOP (NS) | 20 | 98.28 mm² 12.6 x 7.8 |