ZHCSQA7C December 1982 – March 2022 SN54HC257 , SN74HC258
PRODUCTION DATA
请参考 PDF 数据表获取器件具体的封装图。
These 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 (G) input is at a high logic level.
To ensure the high-impedance state during power up or power down, G should be tied to VCC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.