These octal bus transceivers are designed for asynchronous two-way communication between data buses. These 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 output-enable () input can be used to disable the device so that the buses are effectively isolated.

The -1 version of the SN74ALS640B is identical to the standard version, except that the recommended maximum I_OL for the -1 version is increased to 48 mA. There is no -1 version of the SN54ALS640B.

The SN54ALS640B and SN54AS640 are characterized for operation over the full military temperature range of -55°C to 125°C. The SN74ALS640B and SN74AS640 are characterized for operation from 0°C to 70°C.

• Bidirectional Bus Transceivers in High-Density 20-Pin Packages
• Inverting Logic
• Package Options Include Plastic Small-Outline (DW) Packages, Ceramic Chip Carriers (FK), and Standard Plastic (N) and Ceramic (J) 300-mil DIPs

• IOL (Max) (mA)
• 12
• IOH (Max) (mA)
• -12
• Technology Family
• ALS
• Rating
• Military
• Operating temperature range (C)
• -55 to 125

SN54ALS640B的完整型号有：5962-8872701RA、SN54ALS640BJ、SNJ54ALS640BJ，以下是这些产品的关键参数及官网采购报价：

5962-8872701RA，工作温度：-55 to 125，封装：CDIP (J)-20，包装数量MPQ：1个，MSL 等级/回流焊峰值温度：N/A for Pkg Type，引脚镀层/焊球材料：SNPB，TI官网5962-8872701RA的批量USD价格：20.335（1000+）

SN54ALS640BJ，工作温度：-55 to 125，封装：CDIP (J)-20，包装数量MPQ：1个，MSL 等级/回流焊峰值温度：N/A for Pkg Type，引脚镀层/焊球材料：SNPB，TI官网SN54ALS640BJ的批量USD价格：11.664（1000+）

SNJ54ALS640BJ，工作温度：-55 to 125，封装：CDIP (J)-20，包装数量MPQ：1个，MSL 等级/回流焊峰值温度：N/A for Pkg Type，引脚镀层/焊球材料：SNPB，TI官网SNJ54ALS640BJ的批量USD价格：20.335（1000+）