This 8-bit noninverting bus transceiver uses two separate configurable power-supply rails. The SN74LVCH8T245 is optimized to operate with VCCA and VCCB set at 1.65 V to 5.5 V. The A port is designed to track VCCA. VCCA accepts any supply voltage from 1.65 V to 5.5 V. The B port is designed to track VCCB. VCCB accepts any supply voltage from 1.65 V to 5.5 V. This allows for universal low-voltage bidirectional translation between any of the 1.8-V, 2.5-V, 3.3-V, and 5.5-V voltage nodes.
The SN74LVCH8T245 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 input circuitry on both A and B ports is always active and must have a logic HIGH or LOW level applied to prevent excess ICC and ICCZ.
The SN74LVCH8T245 is designed so that the control pins (DIR and OE) are supplied by VCCA.
Active bus-hold circuitry holds unused or undriven inputs at a valid logic state. Use of pullup or pulldown resistors with the bus-hold circuitry is not recommended.
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.
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.
Control Inputs VIH/VIL Levels Are Referenced to VCCA Voltage
VCC Isolation Feature — If Either VCC Input Is at GND, All Are in the High-Impedance State
Fully Configurable Dual-Rail Design Allows Each Port to Operate Over the Full 1.65-V to 5.5-V Power-Supply Range
Bus Hold on Data Inputs Eliminates the Need for External Pullup/Pulldown Resistors
Latch-Up Performance Exceeds 100 mA Per JESD 78, Class II