Texas Instruments SN74AHC245PWRG4

Overview

SN74AHC245PWRG4 from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between two 8-bit buses. It operates across 2 V to 5.5 V V_CC, supports 5 V → 3.3 V voltage translation, and delivers propagation delays as low as 4 ns at 5 V with 15 pF load. It is used in PC motherboard I/O expansion, server memory subsystems, and industrial control backplanes.

For engineers reviewing the SN74AHC245PWRG4 datasheet, SN74AHC245PWRG4 pinout, SN74AHC245PWRG4 application, or SN74AHC245PWRG4 equivalent, key selection criteria include its 20-pin TSSOP package, dual-direction control via DIR input, output-enable (OE) isolation, ±25 mA per-output drive capability, and compatibility with mixed-voltage 3.3 V/5 V system interfaces.

Technical Context

The SN74AHC245PWRG4 implements a CMOS-based octal transceiver architecture with independent DIR and OE control inputs. Its functional modes-A→B, B→A, and high-impedance isolation-are determined solely by logic levels on DIR and OE, eliminating external timing dependencies. The device features overvoltage-tolerant inputs (up to 5.5 V) and slow edge-rate control to suppress output ringing.

It supports both 3.3 V and 5 V operation with guaranteed switching performance: t_PLH/t_PHL ≤ 6.5 ns (V_CC = 5 V, C_L = 15 pF), t_PZH/t_PZL ≤ 10 ns, and static current draw ≤ 40 µA. Thermal resistance in its PW (TSSOP-20) package is R_θJA = 122.3 °C/W, requiring attention to PCB copper area and airflow in high-density layouts.

Key Specifications

Pinout & Package

The SN74AHC245PWRG4 is packaged in a 20-pin TSSOP (PW) with 0.65 mm pitch, body size 6.50 mm × 4.40 mm, and thermal pad omitted (non-RKS variant). Pin 1 is DIR; pins 2–9 and 11–18 are bidirectional A/B I/O channels; pin 10 is GND; pin 20 is V_CC; pin 19 is OE.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC245APWR and 74AVCH245PWRE4, the SN74AHC245PWRG4 uniquely balances 5 V tolerance, industrial temperature range, and robust 3-state isolation - making it the only option among the three qualified for mixed-voltage server, industrial, and telecom infrastructure use cases.

Availability

SN74AHC245PWRG4 is available at Aetrix Electronics and suitable for PC motherboard design, industrial PLC backplane integration, and server memory subsystem development requiring stable component supply, long-term lifecycle support, and RoHS-compliant TSSOP packaging.

Supply support for SN74AHC245PWRG4 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 decades of experience in high-reliability logic and interface solutions.

The SN74AHC245PWRG4 belongs to TI's advanced high-speed CMOS (AHC) logic family, engineered for robust bidirectional bus interfacing in industrial, computing, and communications equipment where voltage translation and noise immunity are critical.

FAQ

What is the maximum recommended operating voltage for SN74AHC245PWRG4?

The absolute maximum V_CC rating for SN74AHC245PWRG4 is 7 V, but the recommended operating range is 2 V to 5.5 V. Operating above 5.5 V risks violating electrical specifications and may cause premature device failure. All timing and drive parameters in the datasheet are guaranteed only within the 2–5.5 V range, and the SN74AHC245PWRG4 is specifically characterized for reliable 5 V system integration.

Can SN74AHC245PWRG4 safely interface a 5 V microcontroller with a 3.3 V FPGA?

Yes - the SN74AHC245PWRG4 accepts input voltages up to 5.5 V regardless of V_CC, so 5 V logic signals from the microcontroller can be applied directly to its A or B ports while V_CC is set to 3.3 V. Its outputs will swing rail-to-rail (0 V to 3.3 V), making them compatible with FPGA I/O banks configured for 3.3 V LVTTL. This eliminates external level-shifting components in the SN74AHC245PWRG4-based interface.

Does SN74AHC245PWRG4 require pull-up resistors on DIR or OE pins?

No external pull-up is required for normal operation, but TI recommends tying OE to V_CC via a pull-up resistor during power-up/down to ensure outputs remain in high-impedance state until firmware initializes control logic. DIR has no default state requirement - its logic level directly defines data direction. For fail-safe isolation, a 10 kΩ pull-up on OE is commonly used, as specified in the SN74AHC245PWRG4 functional description.

What is the thermal performance of SN74AHC245PWRG4 in its TSSOP package?

The SN74AHC245PWRG4 in PW (TSSOP-20) package has a junction-to-ambient thermal resistance (R_θJA) of 122.3 °C/W. At full 8-channel switching with 8 mA per output, power dissipation remains below 50 mW, resulting in <6 °C junction rise above ambient under typical PCB conditions. No heatsink is needed, but 1–2 cm² of internal copper pour connected to GND improves thermal margin in compact layouts.

How does SN74AHC245PWRG4 handle bus contention during direction switching?

The SN74AHC245PWRG4 avoids bus contention through synchronized DIR and OE control: when changing direction, OE should be asserted high (disabling outputs) before toggling DIR, then de-asserted after DIR settles. The device itself has no internal arbitration - contention prevention relies on external timing discipline. Its ±25 mA output limit and 3-state isolation provide hardware-level protection against sustained short-circuit currents during transient mismatches.