Texas Instruments 7802701FA

Overview

7802701FA from Texas Instruments is a military-grade TTL priority encoder that converts eight active-low data inputs (0–7) into three-bit active-low binary (A0–A2) with enable input (EI), enable output (EO), and group select (GS) flags. It operates over −55°C to +125°C, delivers 15 ns typical propagation delay, consumes 12 mA max supply current, and features priority encoding for real-time keyboard or switch matrix decoding in avionics control panels.

For engineers reviewing the 7802701FA datasheet, 7802701FA pinout, 7802701FA application, or 7802701FA equivalent, this page provides verified functional specifications, CFP-16 package terminal mapping, military temperature range validation, cascading interface details (EI/EO/GS), and direct alternatives for legacy system sustainment and obsolescence mitigation.

Technical Context

The 7802701FA implements combinational priority encoding logic where only the highest-order asserted (low) input determines the output code. Its internal architecture uses buffered TTL gates with normalized Series 54/74LS loading, ensuring compatibility with legacy military logic families.

All inputs and outputs are active-low; EI enables encoding (active low), EO signals cascaded enable (active low), and GS indicates valid input activity (active low). The device supports octal expansion via EI/EO chaining without external logic, and exhibits transient behavior during EI transitions requiring strobe synchronization per TI application guidance.

Key Specifications

Pinout & Package

Ceramic Flatpack (CFP) package, 16-pin, 0.3-inch body width, hermetic ceramic construction with parallel leads, designed for high-reliability military PCB mounting and thermal stability across extreme temperature cycles.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar priority encoder applications.

Compared with JM38510/36001BFA and SNJ54LS148W, the 7802701FA offers identical functional, timing, and environmental performance but is distinguished by its specific part marking and TI's current production release under the 7802701FA orderable number - all three are electrically and mechanically interchangeable in fielded systems.

Availability

7802701FA is available at Aetrix Electronics and suitable for avionics control, radiation-hardened instrumentation, and legacy defense electronics requiring stable component supply across extended product lifecycles.

Supply support for 7802701FA 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 manufacturer specializing in analog, embedded processing, and high-reliability logic solutions for aerospace, defense, and industrial markets.

The SN54LS148 family was engineered for military-grade priority encoding in safety-critical systems, delivering deterministic timing, wide temperature operation, and robust TTL interfacing for legacy and sustainment applications.

FAQ

What is the operating temperature range of the 7802701FA?

The 7802701FA is rated for operation from −55°C to +125°C, meeting MIL-PRF-38535 Class B environmental requirements. This range is validated through temperature cycling, thermal shock, and steady-state burn-in tests per military specification, making it suitable for deployment in jet engine bays, space vehicle payloads, and ground-based radar systems where ambient extremes occur.

Does the 7802701FA require external pull-up resistors on its inputs?

No, the 7802701FA does not require external pull-up resistors on its inputs. Its TTL LS inputs have built-in internal pull-down networks and specified input current limits (IIL ≤ −0.4 mA at 0.4 V), allowing direct connection to open-collector or switch-to-ground sources. External pull-ups are only needed if interfacing with non-TTL logic families lacking defined high-state drive capability.

How does the group select (GS) output behave when no inputs are active?

When all inputs 0–7 are high and EI is low, the GS output of the 7802701FA remains high (inactive), indicating no valid encoding condition. GS only goes low when at least one input 0–7 is asserted low while EI is also low - serving as a hardware-valid flag for downstream latching logic to avoid sampling spurious codes during transients.

Can the 7802701FA be used in cascaded configurations with other priority encoders?

Yes, the 7802701FA supports cascading via its EI and EO pins. Connect EO of a lower-priority stage to EI of a higher-priority stage to build 16-, 24-, or 64-input systems. The EO pin goes low only when EI is low and all local inputs are high - enabling hierarchical priority resolution without additional logic gates or timing penalties.

Is the 7802701FA RoHS compliant?

No, the 7802701FA is not RoHS compliant. It uses SNPB (tin-lead) lead finish per MIL-PRF-38535 requirements and is explicitly marked "No" in TI's packaging addendum. This leaded finish ensures solder joint reliability under thermal cycling and mechanical stress in mission-critical military platforms where Pb-free alternatives have not been qualified.