8 Detailed Description

8.1 Overview

The SN74AXC4T774 is a 4-bit, dual-supply noninverting bidirectional voltage level translation device. Ax pins

levels. The A port is able to accept I/O voltages ranging from 0.65 V to 3.6 V, while the B port can accept I/O

voltages from 0.65 V to 3.6 V. A high on DIR allows data transmission from A to B and a low on DIR allows data

transmission from B to A when OE is set to low. When OE is set to high, both Ax and Bx pins are in the high-

impedance state. See Device Functional Modes for a summary of the operation of the control logic.

8.2 Functional Block Diagram

Ax

Bx

DIRx

OE

V

CCA

V

CCB

One of Four Transceivers

8.3 Feature Description

8.3.1 Standard CMOS Inputs

Standard CMOS inputs are high impedance and are typically modeled as a resistor in parallel with the input

capacitance given in the Electrical Characteristics. The worst case resistance is calculated with the maximum

input voltage, given in the Absolute Maximum Ratings, and the maximum input leakage current, given in the

Electrical Characteristics, using ohm's law (R = V ÷ I).

Signals applied to the inputs need to have fast edge rates, as defined by Δt/Δv in Recommended Operating

Conditions to avoid excessive current consumption and oscillations. If a slow or noisy input signal is required, a

device with a Schmitt-trigger input should be used to condition the input signal prior to the standard CMOS input.

8.3.2 Balanced High-Drive CMOS Push-Pull Outputs

A balanced output allows the device to sink and source similar currents. The high drive capability of this device

creates fast edges into light loads so routing and load conditions should be considered to prevent ringing.

Additionally, the outputs of this device are capable of driving larger currents than the device can sustain without

being damaged. The electrical and thermal limits defined in the Absolute Maximum Ratings must be followed at

all times.

The inputs and outputs for this device enter a high-impedance state when the device is powered down, inhibiting

current backflow into the device. The maximum leakage into or out of any input or output pin on the device is

The inputs and outputs for this device enter a high-impedance state when either supply is <100mV.

8.3.5 Over-voltage Tolerant Inputs

Input signals to this device can be driven above the supply voltage so long as they remain below the maximum

input voltage value specified in the Recommended Operating Conditions.

SN74AXC4T774

SCES898A – JULY 2019 – REVISED JULY 2020

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