SN74AXCH4T245 Four-bit bus transceiver with configurable voltage translation, tri-state outputs, and bus-hold inputs

1 Features

• Fully configurable dual-rail design allows each port to operate with a power supply range from 0.65 V to 3.6 V
• Bus-hold on data inputs eliminates the need for external pullup or pulldown resistors
• Operating temperature from –40°C to +125°C
• Multiple direction control pins to allow simultaneous up and down translation
• Glitch-free power supply sequencing
• Up to 380 Mbps support when translating from 1.8 V to 3.3 V
• V_CC isolation feature
• I_off supports partial-power-down mode operation
• Compatible with AVC family level shifters
• Latch-up performance exceeds 100 mA per JESD 78, Class II
• ESD protection exceeds JESD 22
  • 8000-V Human-body model
  • 1000-V Charged-device model

2 Applications

• Enterprise and communications
• Industrial
• Personal electronics
• Wireless infrastructure
• Building automation

3 Description

The SN74AXCH4T245 is a four-bit noninverting bus transceiver that uses two individually configurable power-supply rails. The device is operational with both V_CCA and V_CCB supplies as low as 0.65 V. The A port is designed to track V_CCA, which accepts any supply voltage from 0.65 V to 3.6 V. The B port is designed to track V_CCB, which accepts any supply voltage from 0.65 V to 3.6 V. The SN74AXCH4T245 device is compatible with a single-supply system.

The SN74AXCH4T245 device is designed for asynchronous communication between data buses and transmits data from the A bus to the B bus or from the B bus to the A bus, depending on the logic level of the direction-control inputs (1DIR and 2DIR). The output-enable inputs (1OE and 2OE) are used to disable the outputs so the buses are effectively isolated. All control pins (xDIR and xOE) are referenced to V_CCA.

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. If a supply is present for V_CCA or V_CCB, the bus-hold circuitry always remains active on the A or B inputs respectively, independent of the state of the direction control or output enable pins.

To ensure the high-impedance state of the level shifter I/Os during power up or power down, the xOE pins should be tied to V_CCA through a pullup resistor.

This device is fully specified for partial-power-down applications using the I_off current. The I_off protection circuitry ensures that no excessive current is drawn from or sourced into an input, output, or combined I/O that is biased to a specific voltage while the device is powered down.

The V_CC isolation feature ensures that if either V_CCA or V_CCB is less than 100 mV, all I/O ports enter a high-impedance state by disabling the outputs.

Glitch-free power supply sequencing allows either supply rail to be powered on or off in any order while providing robust power sequencing performance.

1. For all available packages, see the orderable addendum at the end of the data sheet.

Functional Block Diagram

4 Revision History

5 Pin Configuration and Functions

PW Package

16-Pin TSSOP

Top View

RSV Package

16-Pin UQFN

Transparent Top View