2.5-V/3.3-V 18-bit universal bus transceiver with 3-state outputs

The 'ALVTH16601 devices are 18-bit universal bus transceivers designed for 2.5-V or 3.3-V VCC operation, but with the capability to provide a TTL interface to a 5-V system environment.

The devices combine D-type latches and D-type flip-flops to allow data flow in transparent, latched, and clocked modes.

Data flow in each direction is controlled by output-enable (OEAB\ and OEBA\), latch-enable (LEAB and LEBA), and clock (CLKAB and CLKBA) inputs. The clock can be controlled by the clock-enable (CLKENAB\ and CLKENBA\) 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 OEAB\ is active low. When OEAB\ is low, the outputs are active. When OEAB\ 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 OEBA\, LEBA, CLKBA, and CLKENBA\.

This device is fully specified for hot-insertion applications using Ioff and power-up 3-state. The Ioff circuitry disables the outputs, preventing damaging current backflow through the device when it is powered down. The power-up 3-state circuitry places the outputs in the high-impedance state during power up and power down, which prevents driver conflict.

When VCC is between 0 and 1.2 V, the device is in the high-impedance state during power up or power down. However, to ensure the high-impedance state above 1.2 V, 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 is provided to hold unused or floating data inputs at a valid logic level.

The SN54ALVTH16601 is characterized for operation over the full military temperature range of -55°C to 125°C. The SN74ALVTH16601 is characterized for operation from -40°C to 85°C.