This 24-bit noninverting bus transceiver uses two separate configurable power-supply rails. The SN74AVCH24T245 is optimized to operate with VCCA/VCCB set at 1.4 V to 3.6 V. It is operational with VCCA/VCCB as low as 1.2 V. The A port is designed to track VCCA. VCCA accepts any supply voltage from 1.2 V to 3.6 V. The B port is designed to track VCCB. VCCB accepts any supply voltage from 1.2 V to 3.6 V. This allows for universal low-voltage bidirectional translation between any of the 1.2-V, 1.5-V, 1.8-V, 2.5-V, and 3.3-V voltage nodes.
The SN74AVCH24T245 is designed for asynchronous communication between data buses. The device transmits data from the A bus to the B bus or from the B bus to the A bus, depending on the logic level at the direction-control (DIR) input. The output-enable ( OE) input can be used to disable the outputs so the buses are effectively isolated.
The SN74AVCH24T245 is designed so that the control pins (1DIR, 2DIR, 3DIR, 4DIR, 5DIR, 6DIR, 1 OE, 2 OE, 3 OE, 4 OE, 5 OE, and 6 OE) are supplied by VCCA.
This device is fully specified for partial-power-down applications using Ioff. The Ioff circuitry disables the outputs, preventing damaging current backflow through the device when it is powered down.
The VCC isolation feature ensures that if either VCC input is at GND, then both ports are in the high-impedance state.
Active bus-hold circuitry holds unused or undriven inputs at a valid logic state.
To ensure the high-impedance state during power up or power down, OE should be tied to VCCA through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.