Texas Instruments SN74LXCH1T45DTQR

Overview

SN74LXCH1T45 from Texas Instruments is a single-bit, dual-supply noninverting bidirectional bus transceiver with configurable voltage translation (1.1 V to 5.5 V per port), 3-state outputs, and integrated bus-hold inputs. It enables level-shifting between mismatched logic domains-e.g., 1.8 V MCU I/O to 3.3 V peripheral interface-with up to 420 Mbps data rate (3.3 V → 5.0 V), ±4000-V HBM ESD rating, and operation from –40°C to +125°C.

For engineers reviewing the SN74LXCH1T45 datasheet, SN74LXCH1T45 pinout, SN74LXCH1T45 application, or SN74LXCH1T45 equivalent, key selection considerations include dual-rail supply independence (VCCA/VCCB), DIR-controlled directionality, bus-hold elimination of external biasing, Schmitt-trigger DIR input for noise immunity, and VCC isolation behavior during partial power-down.

Technical Context

The SN74LXCH1T45 implements a true dual-supply architecture where A-port I/O and DIR control are referenced to VCCA, while B-port I/O is referenced to VCCB-enabling independent voltage domain operation without level-shifter ICs. Its bus-hold circuitry actively sustains last-valid logic state on A/B data lines, eliminating pull-up/pull-down resistors.

Direction control uses a single DIR input referenced to VCCA; high enables A→B transmission, low enables B→A. The device supports robust power sequencing and includes VCC isolation: if either VCCA or VCCB drops below 100 mV, all I/Os enter high-impedance state, and Ioff-float ensures safe VCC disconnect operation.

Key Specifications

Pinout & Package

SN74LXCH1T45 is packaged in a 6-pin X2SON (DTQ) package with 1.00 mm × 0.80 mm body size and 0.35 mm pitch, optimized for space-constrained portable and embedded designs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar bidirectional voltage translation applications.

Compared with SN74AVCH1T45 and TXS0101, the SN74LXCH1T45 uniquely combines bus-hold, Schmitt-trigger DIR, and VCC isolation-making it optimal for robust, low-component-count level translation in harsh or power-managed environments where signal integrity and fail-safe behavior are critical.

Availability

SN74LXCH1T45 is available at Aetrix Electronics and suitable for industrial sensor interfaces, automotive body electronics, IoT edge node power management, and programmable logic I/O expansion requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SN74LXCH1T45 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader delivering analog and embedded processing solutions for industrial, automotive, personal electronics, and communications markets.

The SN74LXCH1T45 belongs to TI's LXC logic family-designed specifically for low-voltage, low-power, high-noise-immunity bidirectional level translation in space- and energy-constrained embedded systems.

FAQ

What is the minimum operating voltage for SN74LXCH1T45 on each supply rail?

The SN74LXCH1T45 supports a minimum supply voltage of 1.1 V on both VCCA and VCCB rails, enabling compatibility with advanced low-power microcontrollers and FPGAs operating at sub-1.2 V core voltages. This specification is validated across the full –40°C to +125°C temperature range and applies independently to each rail.

Does SN74LXCH1T45 require external pull-up or pull-down resistors on its A and B data lines?

No, the SN74LXCH1T45 does not require external pull-up or pull-down resistors on its A or B data lines because it integrates bus-hold circuitry on both ports. This feature actively maintains the last-valid logic state on floating inputs, eliminating BOM cost and PCB routing overhead while improving reliability in noisy or intermittently connected interfaces.

How does the DIR input behave when left unconnected on SN74LXCH1T45?

The DIR input of the SN74LXCH1T45 includes an integrated static pull-down resistor, so an unconnected (floating) DIR pin defaults to logic low-enabling bidirectional data flow from B to A. This eliminates the need for external pull-down components and simplifies system bring-up in prototypes or low-pin-count designs.

Can SN74LXCH1T45 safely operate when one supply rail is powered down while the other remains active?

Yes, the SN74LXCH1T45 supports safe partial-power-down operation: if either VCCA or VCCB drops below 100 mV, all I/Os automatically enter high-impedance state (VCC isolation), and Ioff-float prevents current backflow. This behavior is fully characterized and guaranteed across –40°C to +125°C, making SN74LXCH1T45 suitable for dynamic power-gating architectures.

What is the maximum data rate supported by SN74LXCH1T45 for 1.8 V to 3.3 V level translation?

For 1.8 V to 3.3 V level translation, the SN74LXCH1T45 supports a maximum data rate of 210 Mbps in the up-translation direction (A=1.8 V → B=3.3 V) and 75 Mbps in the down-translation direction (A=3.3 V → B=1.8 V), as specified in Section 6.12 of the SCES939 datasheet under –40°C to +125°C conditions.