3-STATE OUTPUTS

DESCRIPTION

This 4-bit non-inverting bus transceiver uses two separate

configurable power-supply rails. The A port and control pins (1DIR,2DIR, 1OE and 2 OE ) are designed to track VCCA. VCCA accepts any supply voltage from 1.2V to 3.6V. The B port is designed to track VCCB. VCCB accepts any supply voltage from 1.2V to 3.6V. The U74AVCH4T245 is optimized to operate with VCCA/VCCB set at 1.4V to 3.6V. It is operational with VCCA/VCCB as low as 1.2V.

This allows for universal low-voltage bidirectional translation between any of the 1.2V, 1.5V, 1.8V, 2.5V and 3.3V voltage nodes.

The U74AVCH4T245 device is designed for asynchronous communication between two data buses. The logic levels of the direction-control (DIR) input and the output-enable ( OE ) input activate either the B-port outputs or the A-port outputs or place both output ports into the high-impedance mode. The device transmits data from the A bus to the B bus when the B-port outputs are activated, and from the B bus to the A bus when the A-port outputs are activated.

The U74AVCH4T245 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. To ensure the high-impedance state during power up or power down, 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

FEATURES

* Operation Voltage Range: 1.2 ~ 3.6V

* Control Inputs VIH/VIL Levels Are Referenced to VCCA Voltage

* I/Os Are 4.6V Tolerant

* IOFF Supports Partial Power Down Mode Operation

* Bus Hold On Data Inputs Eliminates the Need for External pull-up/pull down Resistors