The PI74ALVCH16646 is a 16-bit bus transceiver and register designed for 2.3V to 3.6V VCC operation. It can be used as two 8-bit transceivers or one 16-bit transceiver. 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. Four fundamental bus-management functions can be performed. Output Enable (OE) and Direction Control (DIR) inputs are provided to control the transceiver functions. In the transceiver mode, data present at the high-impedance port may be stored in either register or in both. The Select Control (SAB and SBA) inputs can multiplex stored and real-time (transparent mode) data. Circuitry used for Select Control eliminates the typical decoding glitch that occurs in a multiplexer during the transition between stored and real-time data. DIR determines which bus receives data when OE is LOW. In the isolation mode (OE HIGH), A data may be stored in one register and/or B data may be stored in the other register. When an output function is disabled, the input function is still enabled and may be used to store and transmit 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.