Texas Instruments SN74AXCH8T245 device is an 8-bit non-inverting bus transceiver that addresses the voltage between devices operating at the latest voltage nodes (0.7V, 0.8V and 0.9V) and devices operating at industry standard voltage nodes (1.8V) Level mismatch problem (2.5V, 3.3V) and vice versa.
The device operates using two independent power rails (VCCA and VCCB). Data pins A1 to A8 are designed to track VCCA, which accepts any supply voltage from 0.65V to 3.6V. Data pins B1 to B8 are designed to track VCCB, which accepts any supply voltage from 0.65V to 3.6V. Moreover, the device is compatible with single power systems.
The device is intended for asynchronous communication between data buses. This device transfers data from the A bus to the B bus, or from the B bus to the A bus according to the logic level of the direction control inputs (DIR1 and DIR2). The output enable (OE) input is used to disable the output, so the bus is effectively isolated.
The device is designed so the control pins (DIR and OE) are referenced to VCCA.
This device is fully specified for partial power-down applications using Ioff. When the device is powered down, the Ioff circuit disables the output. This prevents current from flowing back into the device, which prevents damage to the device.
VCC isolation ensures that if any VCC input supply is below 100 mV, all level shifter outputs are disabled and placed in a high impedance state. To ensure a high-impedance state of the level shifter I / O during power-up or power-down, OE should be connected to VCCA through a pull-up resistor. The minimum resistance depends on the current sinking capability of the driver.
