Texas Instruments SN74LVC1T45DRLRG4

Overview

SN74LVC1T45 from Texas Instruments is a single-bit dual-supply bus transceiver enabling bidirectional voltage-level translation between 1.65V–5.5V domains, featuring configurable VCCA/VCCB rails, 3-state outputs, ±24mA drive at 3.3V, 4µA max ICC, and VCC isolation for robust partial-power-down operation - used in low-voltage interconnects between microcontrollers and peripherals.

For engineers reviewing the SN74LVC1T45 datasheet, SN74LVC1T45 pinout, SN74LVC1T45 application, or SN74LVC1T45 equivalent, key selection criteria include dual-rail supply flexibility (1.65V–5.5V per rail), direction-control logic referenced to VCCA, Ioff-enabled power-down safety, and verified 420Mbps data rate in 3.3V→5V translation mode.

Technical Context

The SN74LVC1T45 implements asynchronous bidirectional translation via DIR-controlled signal path activation: high DIR enables A→B transmission, low DIR enables B→A transmission. Input circuitry remains active on both ports regardless of DIR state, requiring defined logic levels to avoid excess ICCZ.

Its dual-rail architecture decouples A-port logic thresholds (tied to VCCA) and B-port thresholds (tied to VCCB), supporting mixed-voltage interfaces such as 1.8V↔3.3V, 2.5V↔5V, or 3.3V↔5V without external level-shifting components. VCC isolation ensures both ports enter high-impedance when either VCCA or VCCB = GND.

Key Specifications

Pinout & Package

DRL package is a 6-pin SOT (1.6mm × 1.6mm) NanoFree™封装 using die-as-package construction for minimal footprint and thermal resistance (RθJA = 223.7°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TXB0101DRYR and SN74AVC1T45DBVR, the SN74LVC1T45 offers broader voltage range (up to 5.5V), explicit DIR control for deterministic direction switching, and superior ESD robustness - making it preferred for mixed-voltage industrial and automotive designs where reliability and flexibility outweigh auto-sensing convenience or ultra-high-speed needs.

Availability

SN74LVC1T45 is available at Aetrix Electronics and suitable for industrial sensor interfaces, automotive body control modules, FPGA I/O expansion, and USB-C power delivery negotiation requiring stable component supply and long-term lifecycle support.

Supply support for SN74LVC1T45 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, embedded processing, and connectivity solutions for industrial, automotive, and personal electronics markets.

The SN74LVC1T45 belongs to TI's LVC logic family, designed specifically for low-voltage, low-power bidirectional level translation in space-constrained and thermally sensitive applications - emphasizing robustness, configurability, and compatibility across heterogeneous voltage domains.

FAQ

What is the maximum allowable voltage difference between VCCA and VCCB for reliable operation of the SN74LVC1T45?

The SN74LVC1T45 permits any combination of VCCA and VCCB within 1.65V–5.5V independently; no maximum differential is specified. Both supplies may operate at their extremes simultaneously (e.g., VCCA = 1.65V, VCCB = 5.5V) without violating Absolute Maximum Ratings or degrading switching performance, as confirmed in Section 5.3 Recommended Operating Conditions of the SCES515N datasheet.

Does the SN74LVC1T45 require external pull-up or pull-down resistors on the A or B pins?

No - the SN74LVC1T45 does not require external biasing on A or B I/O pins. However, unused data inputs must be held at VCCI or GND to prevent floating states that increase ICCZ; the DIR pin has no internal termination and must be actively driven high or low. This requirement is explicitly stated in Section 5.3 Note (3) of the SN74LVC1T45 datasheet.

Can the SN74LVC1T45 be used in a unidirectional configuration without connecting the DIR pin to a controller?

Yes - the SN74LVC1T45 can be configured unidirectionally by hard-wiring DIR to VCCA (A→B) or GND (B→A). In this mode, it functions as a fixed-direction translator with identical electrical specs, including Ioff and VCC isolation. This usage is validated in Figure 8-1 (Unidirectional Logic Level-Shifting Application) of the official datasheet.

What is the thermal resistance (RθJA) of the SN74LVC1T45 in the DRL package, and how does it compare to other variants?

The SN74LVC1T45 in DRL (SOT, 6) package has RθJA = 223.7°C/W, per Table 5.4 Thermal Information. This is lower than DBV (215.1°C/W) and DCK (210.9°C/W) but higher than YZP DSBGA (131.0°C/W). The DRL package balances ultra-small footprint (1.6mm × 1.6mm) with acceptable thermal performance for moderate-power applications up to 85°C ambient.

How does the VCC isolation feature behave when VCCA = 0V and VCCB = 3.3V in the SN74LVC1T45?

When VCCA = 0V (GND) and VCCB = 3.3V, the SN74LVC1T45 forces both A and B ports into high-impedance state regardless of DIR logic level, preventing current flow or signal corruption. This behavior is guaranteed by the VCC isolation circuitry and verified in Section 7.3.6 and Table 7-1 of the datasheet, ensuring safe operation during asymmetric power sequencing.