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)\, latch-enable (LEAB and LEBA), and clock (CLKAB and CLKBA) inputs. For A-to-B data flow, the device operates in the transparent mode when LEAB is high. When LEAB is low, the A data is latched if CLKAB is held at a high or low logic level. If LEAB is low, the A data is stored in the latch/flip-flop on the low-to-high transition of CLKAB. When OEAB is high, the outputs are active. When OEAB is low, the outputs are in the high-impedance state. Data flow for B to A is similar to that of A to B, but uses OEBA\, LEBA, and CLKBA. The output enables are complementary (OEAB is active high and OEBA\ is active low). To ensure the high-impedance state during power up or power down, OEBA\ should be tied to VCC through a pullup resistor and OEAB should be tied to GND through a pulldown 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.