Texas Instruments SN54F623J

Overview

SN54F623J from Texas Instruments is a military-grade octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between A and B buses in high-reliability systems. It features dual output-enable inputs (OEAB/OEBA), noninverting logic, local bus-latch capability, and operates across –55°C to 125°C. Used in legacy military avionics backplanes and radiation-tolerant ground support equipment.

For engineers reviewing the SN54F623J datasheet, SN54F623J pinout, SN54F623J application, or SN54F623J equivalent, key selection criteria include military temperature range compliance, 3-state isolation timing (tPZH/tPLZ < 12.4 ns), dual-enable latching behavior, and CDIP-20 package compatibility with through-hole legacy PCBs.

Technical Context

This device implements dual independent enable control: OEAB enables A→B transmission, OEBA enables B→A transmission, and simultaneous low on both enables local latch mode where outputs reinforce inputs. Its TTL-compatible input thresholds (VIL = 0.8 V, VIH = 2 V) and 5-V supply operation ensure interoperability with legacy F-series logic families.

Switching performance is characterized under CL = 50 pF and RL = 500 Ω: propagation delays range from 1.1 ns (tPLH min) to 8.0 ns (tPHL max), while enable-to-output transitions (tPZH/tPLZ) reach up to 12.4 ns at temperature extremes. Output drive strength differs per port-B-side sinks up to 64 mA (IOL), A-side up to 24 mA-supporting asymmetric bus loading.

Key Specifications

Pinout & Package

SN54F623J is housed in a 20-pin Ceramic Dual-In-Line Package (CDIP-J), hermetically sealed for moisture resistance and thermal stability in harsh environments. Pin spacing is 0.1 inch (2.54 mm), with 0.3-inch body width and 0.25-inch height - compatible with MIL-STD-1835 standard sockets and wave-solder tooling.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN54F623J, SNJ54F623J offers identical performance with enhanced certification traceability, while SN54LS623J trades speed and drive strength for reduced power - making it viable only in thermally constrained, timing-insensitive legacy upgrades.

Availability

SN54F623J is available at Aetrix Electronics and suitable for avionics backplanes, military ground test systems, radiation-hardened payloads, and secure crypto module interconnects requiring stable component supply amid long product lifecycles and obsolescence management.

Supply support for SN54F623J 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 U.S.-based semiconductor company founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, aerospace, and defense markets.

The SN54F623J belongs to TI's military-qualified F-series TTL logic family, engineered for high-speed, high-reliability data routing in mission-critical systems where timing predictability and environmental robustness are non-negotiable.

FAQ

What is the maximum operating temperature range for SN54F623J?

The SN54F623J is fully characterized and guaranteed to operate from –55°C to 125°C, meeting MIL-STD-883 requirements for military environmental testing. This range is verified across all electrical parameters including propagation delay, output drive, and input thresholds - no derating is required at temperature extremes. The SN54F623J ceramic DIP package contributes to thermal stability in uncooled chassis applications.

Does SN54F623J support true bidirectional data flow without external control logic?

Yes, the SN54F623J supports true bidirectional operation using its two independent active-low enables: OEAB controls A→B transmission, OEBA controls B→A transmission. When OEAB is low and OEBA is high, data flows A→B; when OEBA is low and OEAB is high, data flows B→A; both high isolates both buses. No external logic is needed to manage direction - the SN54F623J handles it natively.

Can SN54F623J be used to hold bus states during power interruption?

Yes - when both OEAB and OEBA are driven low simultaneously, the SN54F623J enters local bus-latch mode: each output reinforces its corresponding input, and both A and B buses retain their last valid logic states. This behavior persists even if other drivers go high-impedance, making the SN54F623J effective for maintaining bus integrity during brief brownouts or reset sequences in safety-critical systems.

What is the output drive capability of SN54F623J on the B-side versus A-side?

The SN54F623J provides asymmetric drive: B-side outputs (B1–B8) sink up to 64 mA (IOL) and source up to 15 mA (IOH), while A-side outputs (A1–A8) sink up to 24 mA and source up to 3 mA. This design allows the B-side to drive heavier loads - such as terminated transmission lines or multiple TTL inputs - while the A-side conserves drive strength for upstream signal conditioning, a key feature reflected in the SN54F623J's function table and electrical characteristics.

Is SN54F623J pin-compatible with SN74F623N?

Yes - SN54F623J (CDIP-20) and SN74F623N (PDIP-20) share identical pinout, signal assignment, and logic functionality. Both use 20-pin dual-in-line packaging with matching pin 1 location and I/O mapping. However, SN54F623J is rated for –55°C to 125°C and built in ceramic, whereas SN74F623N is commercial-grade (0°C to 70°C) in plastic; mechanical fit is identical, but thermal and reliability specs differ.