SN74LS688NE4

Overview

The SN74LS688NE4 is an 8-bit magnitude and identity comparator from the Texas Instruments SN74LS series. It operates within a supply voltage range of 4.85 V to 5.25 V and supports a maximum low-level output current of 24 mA with a high-level output current of -0.4 mA. The device features a propagation delay of up to 23 ns at 5 V with a 45 pF load. It is housed in a 20-pin PDIP package, measuring 24.33 mm in length, 6.35 mm in width, and 4.57 mm in height. The component is rated for operation between 0°C and +70°C.

Feature Summary

• Performs 8-bit magnitude comparison and identity checking functions
• Provides inverted push-pull (totem-pole) outputs for direct interfacing
• Compatible with standard TTL logic families via LS series characteristics

Applications

• Digital data comparison circuits
• Address decoding systems
• Error detection logic in digital processors

Procurement Notes

Verify the specific ordering suffix NE4 indicates lead-free compliance and environmental specifications as defined by Texas Instruments. Confirm the package type matches the required PCB footprint, specifically the 20-pin PDIP configuration. Ensure the operating temperature range of 0°C to +70°C aligns with the target application environment. Cross-reference the datasheet revision to confirm pinout and electrical characteristics remain consistent with the design requirements.

Selection Notes

Select this component when an 8-bit identity or magnitude comparison function is required within standard TTL logic constraints. The LS series offers a balance of speed and power consumption suitable for general-purpose digital applications. Consider the 20-pin PDIP package for through-hole prototyping or legacy board designs. Verify that the 5 V supply voltage and output drive capabilities meet the downstream logic input requirements.

Part Context

The SN74LS688NE4 belongs to the SN74LS688 family of 8-bit identity comparators manufactured by Texas Instruments. This series is part of the broader SN74xx logic family, designed for compatibility with existing TTL-based systems. The NE4 suffix typically denotes a lead-free variant compliant with RoHS standards, distinguishing it from older non-compliant versions while maintaining identical electrical performance.

Replacement Considerations

Direct replacements include the SN74LS688N for standard packaging or other LS-series equivalents from compatible manufacturers. Verify pin-to-pin compatibility and electrical parameters such as propagation delay and output current before substitution.