Texas Instruments SN74AHC245DWR

Overview

SN74AHC245DWR from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data bus communication between 5 V and 3.3 V domains. It operates from 2 V to 5.5 V, supports ±8 mA output drive at 5 V, features direction (DIR) and output-enable (OE) control, and enables voltage-level translation in server backplanes and embedded microcontroller interfaces.

For engineers reviewing the SN74AHC245DWR datasheet, SN74AHC245DWR pinout, SN74AHC245DWR application, or SN74AHC245DWR equivalent, key selection criteria include 20-pin SOIC package compatibility, 3.3 V/5 V mixed-voltage bus isolation, propagation delay ≤6.5 ns (VCC = 5 V), and guaranteed 3-state output disable timing for clean bus arbitration.

Technical Context

The SN74AHC245DWR implements dual-bus bidirectional data flow controlled by a single DIR input: logic low routes B→A, logic high routes A→B. Its OE input independently disables all outputs into high-impedance state, enabling bus sharing without contention. The device uses advanced CMOS AHC logic for rail-to-rail input tolerance (up to 5.5 V) and controlled edge rates to suppress ringing on transmission lines.

It supports mixed-voltage operation: inputs accept up to 5.5 V regardless of VCC (2–5.5 V), allowing safe interfacing of 5 V peripherals with 3.3 V µCs. Output drive strength is specified at ±4 mA (3.3 V) and ±8 mA (5 V), with guaranteed VOL ≤0.44 V and VOH ≥3.8 V under full load, ensuring noise margins in industrial and telecom backplane environments.

Key Specifications

Pinout & Package

SN74AHC245DWR is housed in a 20-pin SOIC (DW) package measuring 12.80 mm × 10.3 mm (body: 12.80 mm × 7.50 mm), with gull-wing leads and RoHS-compliant NiPdAu finish. It features 100 % matte tin lead plating and is rated MSL Level-1 (unlimited floor life at ≤30 °C / 85 % RH).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC245A and 74AVCH245, the SN74AHC245DWR uniquely bridges 3.3 V and 5 V domains with overvoltage-tolerant inputs, making it irreplaceable in mixed-voltage infrastructure where backward compatibility with legacy 5 V peripherals is mandatory.

Availability

SN74AHC245DWR is available at Aetrix Electronics and suitable for server backplanes, industrial PLCs, wearable health hubs, and telecom line cards requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SN74AHC245DWR 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, with over 90 years of innovation in precision analog, power management, and logic ICs.

The SN74AHC245DWR belongs to TI's AHC logic family, engineered for robust mixed-voltage bus interfacing in industrial, telecom, and computing infrastructure where reliability, wide supply range, and 5 V compatibility are essential.

FAQ

What is the maximum operating voltage for SN74AHC245DWR?

The SN74AHC245DWR supports a supply voltage range of 2 V to 5.5 V. Its absolute maximum rating is 7 V, but sustained operation above 5.5 V violates specifications and risks permanent damage. For reliable 5 V system integration, VCC must be regulated within ±5 % of 5 V, and all unused inputs must be tied to VCC or GND to prevent floating states that could increase ICC or cause undefined behavior in the SN74AHC245DWR.

Can SN74AHC245DWR translate 5 V signals to a 3.3 V microcontroller?

Yes - the SN74AHC245DWR accepts input voltages up to 5.5 V regardless of VCC level, making it ideal for down-translation. When powered at 3.3 V, its inputs safely interface with 5 V logic outputs, and its 3.3 V-compatible outputs drive standard 3.3 V CMOS inputs. This capability is explicitly validated in TI's datasheet Section 7.3 and eliminates external level-shifting components in designs using the SN74AHC245DWR.

What is the thermal resistance (RθJA) of SN74AHC245DWR in SOIC package?

The SN74AHC245DWR in SOIC (DW) package has a junction-to-ambient thermal resistance (RθJA) of 96.2 °C/W, as measured per JEDEC JESD51 standards. This value assumes standard 2-layer PCB layout with 1 in² copper pour. For high-power-density applications, thermal performance improves significantly with internal layer copper planes and thermal vias - design guidance is provided in TI's application note SZZA039 for optimizing SN74AHC245DWR thermal management.

How does the DIR pin control data flow direction in SN74AHC245DWR?

The DIR pin on the SN74AHC245DWR is an active-high direction control: when DIR = HIGH, data flows from Port A to Port B; when DIR = LOW, data flows from Port B to Port A. This bidirectional routing occurs simultaneously across all eight channels. The function is fully static - no clock or timing constraints apply - and is detailed in Table 7-1 (Function Table) of the SN74AHC245DWR datasheet.

Is SN74AHC245DWR pin-compatible with older 74LS245 or 74HC245 variants?

No - while SN74AHC245DWR shares identical pinout (20-pin SOIC) and functional mapping with 74HC245, it is not pin-compatible with 74LS245 due to differing electrical characteristics and drive architecture. The SN74AHC245DWR uses CMOS AHC logic with rail-to-rail inputs and complementary outputs, whereas 74LS245 is bipolar TTL. Direct substitution may cause timing violations or excessive loading; always verify VIL/VIH thresholds and fanout in the target system before replacing with SN74AHC245DWR.