The TCA9406 is a 2-bit bidirectional I2C and SMBus voltage-level translator with an output enable (OE) input. It is operational from 1.65 V to 3.6 V on the A-side, referenced toVCCA, and from 2.3 V to 5.5 V on the B-side, referenced to VCCB. This allows the device to interface between lower and higher logic signal levels at any of the typical 1.8-V, 2.5-V, 3.3-V, and
5-V supply rails.
The OE input pin is referenced to VCCA, can be tied directly to VCCA, but it is also 5.5-V tolerant. The OE pin can also be controlled and set to a logic low to place all the SCL and SDA pins in a high-impedance state, which significantly reduces the quiescent current consumption.
Under normal I2C and SMBus operation or other open-drain configurations, the TCA9406 can support up to 2 Mbps; therefore, it is compatible with standard I2C speeds where the frequency of SCL is 100 kHz (Standard-mode), 400 kHz (Fast-mode), or 1 MHz (Fast-mode Plus). The device can also be used as a general purpose level translator, and when the A- and B-side ports are both driven with push-pull devices the TCA9406 can support up to 24 Mbps.
The TCA9406 features internal 10-kΩ pullup resistors on SCL_A, SDA_A, SCL_B, and SDA_B. Additional external pullup resistors can be added to the bus to reduce the total pullup resistance and speed up rising edges.