The 74ALVCH16601 is an 18-bit universal transceiver featuring non-inverting 3-State bus compatible outputs in both send and receive directions. Data flow in each direction is controlled by output enable (OE
AB and OE
BA) latch enable (LEAB and LEBA ) , and clock (CPAB and CPBA) inputs. For A-to-B data flowthe device operates in the transparent mode when LEAB is High. When LEAB is Low, the A data is latched if CPAB is held at a High or Low logic level. If LEAB is Low, the A-bus data is stored in the latch/flip-flop on the Low-to-High transition of CPAB. When OE
AB is Low, the outputs are active. When OE
AB is High, the outputs are in the high-impedance state. The clocks can be controlled with the clock-enable inputs (CE
Data flow for B-to-A is similar to that of A-to-B but uses OE
BA LEBA and CPBA.
To ensure the high impedance state during power up or power down, OE
BA and OE
AB should be tied to VCC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking/current-sourcing capability of the driver. Active bus-hold circuitry is provided to hold unused or floating data inputs at a valid logic level.