These 18-bit universal bus transceivers combine D-type latches and D-type flip-flops to allow data flow in transparent, latched, clocked, and clock-enabled modes. Data flow in each direction is controlled by output-enable ( and ), latch-enable (LEAB and LEBA), and clock (CLKAB and CLKBA) inputs. The clock can be controlled by the clock-enable ( and ) 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. Output enable is active low. When is low, the outputs are active. When is high, the outputs are in the high-impedance state. Data flow for B to A is similar to that of A to B, but uses , LEBA, CLKBA, and . To ensure the high-impedance state during power up or power down, 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. The SN54ABT16601 is characterized for operation over the full military temperature range of -55°C to 125°C. The SN74ABT16601 is characterized for operation from -40°C to 85°C.