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)
• 48
• IOH (Max) (mA)
• -15
• Technology Family
• ALS
• Rating
• Catalog
• Operating temperature range (C)
• 0 to 70

SN74ALS640B-1的完整型号有：SN74ALS640B-1DW、SN74ALS640B-1DWR、SN74ALS640B-1N、SN74ALS640B-1NSR，以下是这些产品的关键参数及官网采购报价：

SN74ALS640B-1DW，工作温度：0 to 70，封装：SOIC (DW)-20，包装数量MPQ：25个，MSL 等级/回流焊峰值温度：Level-1-260C-UNLIM，引脚镀层/焊球材料：NIPDAU，TI官网SN74ALS640B-1DW的批量USD价格：1.566（1000+）

SN74ALS640B-1DWR，工作温度：0 to 70，封装：SOIC (DW)-20，包装数量MPQ：2000个，MSL 等级/回流焊峰值温度：Level-1-260C-UNLIM，引脚镀层/焊球材料：NIPDAU，TI官网SN74ALS640B-1DWR的批量USD价格：1.305（1000+）

SN74ALS640B-1N，工作温度：0 to 70，封装：PDIP (N)-20，包装数量MPQ：20个，MSL 等级/回流焊峰值温度：N/A for Pkg Type，引脚镀层/焊球材料：NIPDAU，TI官网SN74ALS640B-1N的批量USD价格：1.501（1000+）

SN74ALS640B-1NSR，工作温度：0 to 70，封装：SO (NS)-20，包装数量MPQ：2000个，MSL 等级/回流焊峰值温度：Level-1-260C-UNLIM，引脚镀层/焊球材料：NIPDAU，TI官网SN74ALS640B-1NSR的批量USD价格：1.501（1000+）

14-24-LOGIC-EVM — 支持 14 到 24 引脚 PW、DB、D、DW、NS、DYY 和 DGV 封装的通用逻辑 EVM

该 EVM 设计用于支持采用 14 至 24 引脚 D、DW、DB、NS、PW、DYY 或 DGV 封装的任何逻辑器件。