CD74HCT646屬于集成電路（IC）的緩沖器驅(qū)動(dòng)器接收器收發(fā)器。由美國德州儀器公司制造生產(chǎn)的CD74HCT646緩沖器，驅(qū)動(dòng)器，接收器，收發(fā)器邏輯緩沖器、驅(qū)動(dòng)器、接收器和收發(fā)器允許隔離對(duì)某個(gè)電路的邏輯信號(hào)的訪問，以用于另一電路。緩沖器將其輸入信號(hào)（不變或反相）傳遞到其輸出，并可能用于清除弱信號(hào)或驅(qū)動(dòng)負(fù)載。在布爾邏輯仿真器中，緩沖器主要用于增加傳播延遲。邏輯接收器和收發(fā)器允許在數(shù)據(jù)總線之間進(jìn)行隔離通信。

2-V to 6-V VCC Operation (CD54HC646)

4.5-V to 5.5-V VCC Operation (CD74HCT646)

Wide Operating Temperature Range of

–55°C to 125°C

Balanced Propagation Delays and

Transition Times

Standard Outputs Drive Up To 15 LS-TTL

Loads

Significant Power Reduction Compared to

LS-TTL Logic ICs

Inputs Are TTL-Voltage Compatible

(CD74HCT646)

Independent Registers for A and B Buses

Multiplexed Real-Time and Stored Data

True Data Paths

description/ordering information

The CD54HC646 and CD74HCT646 consist of bus-transceiver circuits with 3-state outputs, D-type flip-flops,

and control circuitry arranged for multiplexed transmission of data directly from the input bus or from the internal

registers. Data on the A or B bus is clocked into the registers on the low-to-high transition of the appropriate

clock (CLKAB or CLKBA) input. Figure 1 illustrates the four fundamental bus-management functions that can

be performed with these devices.

Output-enable (OE) and direction-control (DIR) inputs control the transceiver functions. In the transceiver

mode, data present at the high-impedance port can be stored in either or both registers.

The select-control (SAB and SBA) inputs can multiplex stored and real-time (transparent mode) data. DIR

determines which bus receives data when OE is active (low). In the isolation mode (OE high), A data can be

stored in one register and/or B data can be stored in the other register.

When an output function is disabled, the input function still is enabled and can be used to store data. Only one

of the two buses, A or B, can be driven at a time.

To ensure the high-impedance state during power up or power down, OE 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.