20-bit dual supply translating transceiver with configurable voltage translation; 3-state

The 74AVCH20T245 is a 20-bit, dual supply transceiver that enables bi-directional voltage level translation. The device can be used as two 10-bit transceivers or as a single 20-bit transceiver. It features four 10-bit input-output ports (1An, 1Bn and 2An, 2Bn), two output enable inputs (nOE), two direction inputs (nDIR) and dual supplies (VCC(A) and VCC(B)). VCC(A) and VCC(B) can be independently supplied at any voltage between 0.8 V and 3.6 V making the device suitable for bi-directional voltage level translation between any of the low voltage nodes: 0.8 V, 1.2 V, 1.5 V, 1.8 V, 2.5 V and 3.3 V. The 1An and 2An ports, nOE and nDIR are referenced to VCC(A), the 1Bn and 2Bn ports are referenced to VCC(B). A HIGH on a 1DIR allows transmission from 1An to 1Bn and a LOW on 1DIR allows transmission from 1Bn to 1An. A HIGH on nOE causes the outputs to assume a HIGH impedance OFF-state.

The device is fully specified for partial power-down applications using IOFF. The IOFF circuitry disables the output, preventing any damaging backflow current through the device when it is powered down. In suspend mode when either VCC(A) or VCC(B) are at GND level, all output ports will assume a high impedance OFF-state. The bus hold circuitry on the powered-up side always stays active.

The 74AVCH20T245 has active bus hold circuitry which is provided to hold unused or floating data inputs at a valid logic level. This feature eliminates the need for external pull-up or pull-down resistors.