Texas Instruments SN74HC245PWRG4

Overview

SN74HC245PWRG4 from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between A and B buses in 3.3 V or 5 V digital systems. It features ±6-mA output drive at 5 V, 12 ns typical propagation delay (VCC = 6 V, CL = 50 pF), and operates across 2 V to 6 V supply range - enabling level-shifting between mixed-voltage subsystems in PCs, network switches, and industrial controllers.

For engineers reviewing the SN74HC245PWRG4 datasheet, SN74HC245PWRG4 pinout, SN74HC245PWRG4 application, or SN74HC245PWRG4 equivalent, key selection criteria include direction-control (DIR) and output-enable (OE) logic behavior, 3-state isolation timing (ten/tdis), thermal resistance (RθJA = 99.7 °C/W in TSSOP), and compatibility with LSTTL loads (up to 15 units).

Technical Context

The SN74HC245PWRG4 implements dual-bus bidirectional communication using a single DIR input to select data flow direction (A→B or B→A) and an active-low OE input to place all outputs in high-impedance state. Its CMOS design ensures low static current (80 µA max ICC) and controlled edge rates to minimize ringing on transmission lines.

Functionally, it supports asynchronous operation without external clocks; timing is governed solely by input transitions and load capacitance. The device complies with standard HC logic thresholds (VIH = 3.15 V, VIL = 1.35 V at VCC = 4.5 V) and tolerates input transition times down to 400 ns (VCC = 6 V), making it suitable for legacy TTL interfacing and modern low-power embedded buses.

Key Specifications

Pinout & Package

TSSOP-20 (PW) package: 6.50 mm × 4.40 mm body, 0.65 mm lead pitch, surface-mount, RoHS-compliant NIPDAU finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC245PWRG4, SN74LVC245APWR offers superior speed and drive in 3.3 V domains but sacrifices 5 V tolerance, while 74AC245MTCX delivers higher performance at 5 V with significantly increased supply current - making SN74HC245PWRG4 the optimal balance of voltage flexibility, power efficiency, and signal integrity for mixed-voltage embedded interfaces.

Availability

SN74HC245PWRG4 is available at Aetrix Electronics and suitable for PC backplanes, industrial PLC I/O modules, and network switch fabric interfaces requiring stable component supply across extended production lifecycles.

Supply support for SN74HC245PWRG4 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 logic solutions with over 50 years of innovation in industrial, automotive, and communications markets.

The SN74HC245PWRG4 belongs to TI's 74HC logic family - engineered for reliable, low-power bidirectional bus interfacing in commercial and industrial systems where voltage flexibility and noise immunity are critical.

FAQ

What is the maximum recommended load capacitance for SN74HC245PWRG4 to maintain specified timing?

The SN74HC245PWRG4 switching characteristics are characterized at CL = 50 pF and CL = 150 pF per output. For guaranteed 12 ns typical tpd (VCC = 6 V), total load capacitance should not exceed 50 pF. At 150 pF, tpd increases to 15 ns - still within specification but requiring timing margin review in high-speed designs. Layout parasitics must be included in total CL calculation.

Can SN74HC245PWRG4 safely interface a 3.3 V microcontroller with a 5 V EEPROM?

Yes, SN74HC245PWRG4 supports 2–6 V operation and has 5 V-tolerant inputs. When powered at 3.3 V, its outputs swing rail-to-rail (0–3.3 V), which meets VIH minimum (1.35 V) of standard 5 V EEPROMs. For reliable 5 V EEPROM reads, ensure OE and DIR are driven by 3.3 V logic compatible with 5 V input thresholds - no level shifter needed on control lines.

How does the SN74HC245PWRG4 handle bus contention during direction switching?

The SN74HC245PWRG4 does not include built-in bus contention protection. During DIR transitions, both A and B ports may briefly drive simultaneously if OE remains active. To prevent damage, ensure DIR changes only when OE is high (outputs disabled), or implement external arbitration logic. TI recommends verifying timing waveforms in actual layout to avoid exceeding ±35 mA per output absolute maximum rating.

Is SN74HC245PWRG4 pin-compatible with other TSSOP-20 octal transceivers like SN74LVC245A?

SN74HC245PWRG4 and SN74LVC245APWR share identical TSSOP-20 pinout (PIN 1 = DIR, PIN 19 = OE, PIN 20 = VCC), making them mechanically interchangeable. However, electrical differences - including VCC range, output drive, and input thresholds - require schematic and firmware validation before substitution. No guarantee of functional drop-in replacement.

What is the recommended bypass capacitor configuration for SN74HC245PWRG4 in high-noise industrial environments?

TI specifies a 0.1 µF ceramic capacitor placed within 3 mm of the VCC pin (PIN 20) and GND (PIN 10) for SN74HC245PWRG4. In electrically noisy settings (e.g., motor drives, relay banks), add a parallel 1 µF X7R ceramic capacitor to suppress lower-frequency ripple. Avoid electrolytic capacitors due to ESL limitations above 1 MHz.