This 18-bit universal bus transceiver is designed for 1.65-V to 3.6-V VCC operation. Data flow in each direction is controlled by output-enable (OEAB\ and OEBA\) and clock-enable (CLKENBA\) inputs. For the A-to-B data flow, the data flows through a single buffer. The B-to-A data can flow through a four-stage pipeline register path, or through a single register path, depending on the state of the select (SEL\) input. Data is stored in the internal registers on the low-to-high transition of the clock (CLK) input, provided that the appropriate CLKENBA\ input is low. The B-to-A data transfer is synchronized with CLK. 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. Active bus-hold circuitry holds unused or undriven inputs at a valid logic state. Use of pullup or pulldown resistors with the bus-hold circuitry is not recommended.