Texas Instruments SN74ALVCH245DWR

Overview

SN74ALVCH245DWR from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between 1.65-V to 3.6-V buses. It features ±24-mA output drive at 3.3 V, 3.4-ns max propagation delay, bus-hold circuitry eliminating external resistors, and operates across –40°C to 85°C. It serves in voltage-level-flexible system interconnects such as FPGA-to-ASIC or microcontroller peripheral expansion.

For engineers reviewing the SN74ALVCH245DWR datasheet, SN74ALVCH245DWR pinout, SN74ALVCH245DWR application, or SN74ALVCH245DWR equivalent, key selection criteria include VCC range compatibility (1.65–3.6 V), 3-state isolation timing (ten/tdis ≤ 5.5 ns at 3.3 V), bus-hold input retention, and SOIC-20 package thermal performance (θJA = 58°C/W).

Technical Context

This device implements dual-directional 8-bit data routing controlled by DIR and OE inputs: DIR = L enables B→A transmission; DIR = H enables A→B transmission; OE = H forces all outputs into high-impedance state. Its bus-hold circuitry actively maintains valid logic levels on undriven A/B port inputs without external biasing.

It supports mixed-voltage system interfacing due to its wide VCC range and level-shift-tolerant I/O thresholds (VIH/VIL scale with VCC). Input transition rate limit of 10 ns/V ensures robust noise immunity during fast edge transitions, while latch-up immunity exceeds 100 mA per JESD 78 Class II.

Key Specifications

Pinout & Package

SN74ALVCH245DWR uses a 20-pin SOIC (DW) package with 7.5-mm body width, 2.65-mm max height, and 1.27-mm lead pitch. Pin 1 is located at the top-left corner with a beveled edge indicator.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal bus transceiver applications.

Compared with SN74LVC245A and 74AVC245, SN74ALVCH245DWR uniquely combines bus-hold functionality, SOIC-20 pin compatibility, and full 1.65–3.6-V operation - making it optimal for legacy design refreshes and industrial systems where input state integrity is non-negotiable.

Availability

SN74ALVCH245DWR is available at Aetrix Electronics and suitable for industrial PLC backplanes, FPGA I/O expansion, automotive body control modules, embedded microcontroller peripheral bridges, and medical imaging subsystems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SN74ALVCH245DWR 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 specializing in analog, embedded processing, and connectivity technologies, with over 90 years of innovation in industrial, automotive, and communications markets.

The SN74ALVCH245DWR belongs to TI's ALVC/ALVCH logic family, engineered for low-voltage, high-speed bidirectional bus interfacing in mixed-supply systems where signal integrity, power efficiency, and robustness are critical.

FAQ

What is the recommended power-up sequence for SN74ALVCH245DWR?

TI specifies that OE must be held high (via pullup to VCC) during power-up to ensure all outputs remain in high-impedance state until VCC stabilizes. For SN74ALVCH245DWR, connect a 10-kΩ resistor from OE to VCC; DIR may be left floating or tied to either rail, but bus-hold will maintain its last valid state. This prevents bus contention during supply ramp.

Does SN74ALVCH245DWR support hot-swap operation?

Yes - SN74ALVCH245DWR supports hot-swap due to its bus-hold circuitry, which maintains valid logic levels on undriven A/B inputs, and its absolute maximum ratings allowing VI/O up to VCC + 0.5 V. However, OE must be asserted high before insertion to avoid back-driving live buses; TI recommends using series resistors on A/B lines in high-reliability hot-swap designs.

Can SN74ALVCH245DWR interface between 1.8-V and 3.3-V buses without level shifters?

Yes - SN74ALVCH245DWR operates natively across 1.65–3.6 V and accepts input voltages down to 0.35×VCC (e.g., 0.63 V at 1.8 V) and up to VCC + 0.5 V. When VCC = 3.3 V, it correctly interprets 1.8-V logic highs (≥1.7 V) and lows (≤0.8 V), enabling direct 1.8-V ↔ 3.3-V translation without external components.

What is the thermal resistance (θJA) of SN74ALVCH245DWR in its SOIC-20 package?

The junction-to-ambient thermal resistance (θJA) for SN74ALVCH245DWR in the SOIC (DW) package is 58°C/W, measured under standard JEDEC test conditions (1-layer 2-oz copper, 1-in² pad). This value assumes no internal power dissipation beyond typical switching (Cpd ≈ 31 pF), and confirms suitability for industrial ambient temperatures up to 70°C with natural convection.

How does bus-hold functionality affect PCB layout for SN74ALVCH245DWR?

Bus-hold eliminates the need for external pullup/pulldown resistors on A1–A8 and B1–B8 pins, reducing component count and board area. However, TI explicitly warns against using pull resistors *with* bus-hold enabled, as they create conflicting current paths and increase static power. Layout should route A/B traces with controlled impedance and minimize stub length to preserve signal integrity during high-speed toggling.