The ’HCT257 devices are designed to multiplex signals from 4-bit data sources to 4-output data lines in bus-organized systems. The 3-state outputs do not load the data lines when the output-enable (OE)\ input is at the high logic level.

To ensure the high-impedance state during power up or power down, OE\ should be tied to V_CC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.

• Operating Voltage Range of 4.5 V to 5.5 V
• High-Current 3-State Outputs Interface Directly With System Bus
• Typical tpd = 17 ns
• Low Power Consumption, 80-A Max ICC
• ±6-mA Output Drive at 5 V
• Low Input Current of 1 A Max
• Inputs Are TTL-Voltage Compatible
• Provide Bus Interface From Multiple Sources in High-Performance Systems
• Buffered Inputs and Outputs

• Technology Family
• HCT
• Function
• Digital Multiplexer
• Configuration
• 2:1
• Number of channels (#)
• 4
• Operating temperature range (C)
• -40 to 85
• Rating
• Catalog

SN74HCT257的完整型号有：SN74HCT257D、SN74HCT257DR、SN74HCT257N，以下是这些产品的关键参数及官网采购报价：

SN74HCT257D，工作温度：-40 to 85，封装：SOIC (D)-16，包装数量MPQ：40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SN74HCT257D的批量USD价格：.37（1000+）

SN74HCT257DR，工作温度：-40 to 85，封装：SOIC (D)-16，包装数量MPQ：2500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SN74HCT257DR的批量USD价格：.13（1000+）

SN74HCT257N，工作温度：-40 to 85，封装：PDIP (N)-16，包装数量MPQ：25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SN74HCT257N的批量USD价格：.196（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。