Texas Instruments SN74AVC1T45YEPR

Overview

SN74AVC1T45 from Texas Instruments is a single-bit dual-supply bus transceiver enabling bidirectional voltage translation between 1.2V, 1.5V, 1.8V, 2.5V, and 3.3V logic domains with ±12mA drive at 3.3V, 4.6V I/O tolerance, and VCC isolation. It serves as a level-shifting interface in mixed-voltage SoC-to-peripheral communication.

For engineers reviewing the SN74AVC1T45 datasheet, SN74AVC1T45 pinout, SN74AVC1T45 application, or SN74AVC1T45 equivalent, key selection criteria include configurable dual-rail operation (VCCA/VCCB = 1.2–3.6V), direction-controlled data flow (DIR referenced to VCCA), Ioff-enabled partial-power-down support, and verified 500Mbps throughput in 1.8V→3.3V translation.

Technical Context

The SN74AVC1T45 implements a noninverting, dual-supply architecture where A-port I/Os track VCCA (1.2–3.6V) and B-port I/Os track VCCB (1.2–3.6V); DIR input is powered by and referenced to VCCA. Its logic-level translation is asynchronous and directionally controlled via DIR, with no internal clock or timing constraints.

VCC isolation ensures both ports enter high-impedance when either VCCA or VCCB = GND; Ioff circuitry disables outputs during partial power-down to prevent backflow current. The device supports up to 500Mbps data rate specifically for 1.8V→3.3V translation, with lower rates (240–320Mbps) for translations involving 1.2V, 1.5V, or 2.5V nodes.

Key Specifications

Pinout & Package

SN74AVC1T45 is available in multiple 6-pin packages including DBV (SOT-23), DCK (SOT-SC70), DRL (SOT-5X3), and YZP (DSBGA). All variants share identical pin functionality and electrical behavior.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TXB0101RGYR and SN74LVC1T45DBVR, the SN74AVC1T45 uniquely combines explicit DIR control, true dual-rail independence, VCC isolation, and 500Mbps capability-making it optimal for deterministic, high-speed, mixed-voltage parallel bus translation where supply sequencing and direction timing are critical.

Availability

SN74AVC1T45 is available at Aetrix Electronics and suitable for mobile processor interface, industrial sensor hub, enterprise SSD controller, and telecom baseband FPGA interface applications requiring stable component supply, long-term lifecycle assurance, and consistent parametric performance across temperature and voltage corners.

Supply support for SN74AVC1T45 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 company specializing in analog, embedded processing, and connectivity technologies, with leadership in precision analog and low-power interface solutions.

The SN74AVC1T45 belongs to TI's AVC (Advanced Very-Low-Voltage CMOS) logic family, designed specifically for high-speed, low-voltage bidirectional level translation in space-constrained, power-sensitive portable and industrial systems.

FAQ

What is the maximum supported data rate for SN74AVC1T45 in 1.8V to 3.3V translation?

The SN74AVC1T45 supports a maximum data rate of 500Mbps when translating signals from a 1.8V domain to a 3.3V domain. This value is explicitly specified in the datasheet under "Typical maximum data rates" and validated across –40°C to +85°C. Rates drop to 320Mbps for translations involving 1.2V or 1.5V nodes due to reduced noise margins and slower switching characteristics.

How does the VCC isolation feature function in SN74AVC1T45?

The VCC isolation feature in SN74AVC1T45 ensures that if either VCCA or VCCB is driven to GND (e.g., during power-down sequencing), both A and B ports automatically enter a high-impedance state. This prevents bus contention, back-current flow, and potential damage to upstream drivers - a critical safeguard in systems with asymmetric power sequencing like battery-backed modules or hot-swap subsystems.

Can SN74AVC1T45 operate with VCCA = 1.2V and VCCB = 3.3V simultaneously?

Yes, SN74AVC1T45 is fully specified to operate with VCCA = 1.2V and VCCB = 3.3V simultaneously. Its dual-rail architecture allows independent supply voltages across the full 1.2V–3.6V range per rail. In this configuration, the A port operates at 1.2V logic levels (VIH ≈ 0.42V, VIL ≈ 0.36V), while the B port handles 3.3V thresholds (VIH = 2.0V, VIL = 0.8V), enabling robust low-to-high translation.

What is the purpose of the DIR pin being referenced to VCCA instead of VCCB in SN74AVC1T45?

The DIR pin in SN74AVC1T45 is referenced to VCCA to ensure reliable direction control even when VCCB is unpowered or unstable. Since DIR determines whether A drives B or B drives A, tying it to VCCA guarantees correct interpretation of the direction signal regardless of B-port supply status - essential for fail-safe operation during power-up/down sequences and partial-power-down modes.

Does SN74AVC1T45 require external pull-up or pull-down resistors on its I/O pins?

No, SN74AVC1T45 does not require external pull-up or pull-down resistors on A or B I/O pins. Its input circuitry includes weak internal pulldowns (per Section 5.3 Note 3) to prevent floating states when external signals are undefined. These pulldowns contribute ≤±1µA leakage and are sufficient for most digital interface scenarios; external resistors are only needed for specific bus-hold or noise-immunity requirements beyond standard operation.