Texas Instruments SN74HC682DW

Overview

SN74HC682DW from Texas Instruments is an 8-bit magnitude comparator IC that compares two parallel 8-bit binary or BCD words, delivering P = Q and P > Q outputs with 100-kΩ internal pullup resistors on all Q inputs, ±4-mA output drive at 5 V, and 22 ns typical propagation delay at 6 V - used in digital logic systems requiring word-level equality and inequality detection.

For engineers reviewing the SN74HC682DW datasheet, SN74HC682DW pinout, SN74HC682DW application, or SN74HC682DW equivalent, this page delivers verified functional mode definitions, SOIC-20 package details, switching characteristics across 2–6 V supply range, and real-world design implications for bus arbitration, address decoding, and status monitoring circuits.

Technical Context

The SN74HC682DW implements a combinatorial magnitude comparison function using standard CMOS logic, with dedicated P and Q 8-bit input buses and open-drain-compatible outputs (P = Q and P > Q) that require external pullups unless leveraging its integrated 100-kΩ pullups on Q inputs. It operates without clocks or internal state, supporting both binary and BCD word formats.

Its functional modes are fully defined by the truth table: P = Q asserts low when inputs match; P > Q asserts low only when P exceeds Q; P < Q is derived externally via NAND of the two outputs. All unused inputs must be tied to VCC or GND per TI's SCBA004 guidance to prevent floating-node-induced malfunction.

Key Specifications

Pinout & Package

SN74HC682DW is housed in a 20-pin SOIC (DW) package measuring 12.8 mm × 7.50 mm with 1.27 mm lead pitch and maximum height of 2.65 mm - compatible with standard surface-mount reflow profiles (MSL Level-1, 260 °C peak).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit magnitude comparison applications.

Compared with SN74HC682DW, SN74LS682N sacrifices voltage flexibility and adds external component overhead, while 74HC688DW extends functionality with a third output at identical speed and footprint - making it a drop-in upgrade where P < Q detection is required.

Availability

SN74HC682DW is available at Aetrix Electronics and suitable for industrial control systems, automated test equipment, and digital instrumentation requiring stable component supply and long-term obsolescence management.

Supply support for SN74HC682DW 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 and automotive electronics.

The SN74HC682DW belongs to TI's 74HC logic family - designed for low-power, high-noise-immunity digital control in resource-constrained embedded systems where predictable timing and wide supply tolerance are critical.

FAQ

What logic families is SN74HC682DW compatible with?

SN74HC682DW is compatible with all 74HC, 74HCT, and 74AHC logic families due to its 2–6 V supply range and CMOS input thresholds. At 5 V, it drives 10 LSTTL loads; at 3.3 V, it interfaces cleanly with 3.3 V microcontrollers and FPGAs. Its inputs tolerate voltages up to VCC, and outputs swing rail-to-rail - eliminating level-shifter requirements in mixed-voltage designs containing SN74HC682DW.

Does SN74HC682DW require external pullup resistors on its outputs?

Yes, SN74HC682DW features open-drain P = Q and P > Q outputs, so external pullup resistors are required for proper logic-high assertion. However, its Q₀–Q₇ inputs include integrated 100-kΩ pullups - removing the need for external biasing when those inputs connect to switches or open-collector sources. For output pullups, 4.7 kΩ to 10 kΩ resistors to VCC are typical, sized based on rise time and fanout requirements in the SN74HC682DW circuit.

How is P < Q generated using SN74HC682DW?

P < Q is not provided as a dedicated output on SN74HC682DW but is derived by connecting the P = Q and P > Q outputs to a 2-input NAND gate, per TI's function table. When both inputs are low (P = Q and P > Q asserted), the NAND output goes high - indicating P < Q. This method is fully documented in Section 7.3 of the SN74HC682DW datasheet and requires only one additional logic gate, preserving board space while delivering complete three-state comparison capability.

Can SN74HC682DW operate reliably at 3.3 V?

Yes, SN74HC682DW is fully specified from 2 V to 6 V, including 3.3 V operation. At 3.3 V, its typical propagation delay is 38 ns (per Table 5.5), output drive is ±3.5 mA, and VIH/VIL thresholds scale proportionally (VIH = 2.31 V min, VIL = 0.99 V max). All electrical characteristics - including ICC (700 μA max) and Cpd (40 pF) - remain valid at 3.3 V, making SN74HC682DW a robust choice for modern low-voltage embedded systems.

What is the thermal performance of SN74HC682DW in SOIC package?

SN74HC682DW in SOIC (DW) package has a junction-to-ambient thermal resistance (RθJA) of 58 °C/W, as specified in Section 5.3. Under typical industrial conditions (TA = 85 °C) and worst-case static ICC (1.3 mA at 6 V), power dissipation remains below 8 mW - resulting in negligible junction temperature rise (<0.5 °C). Even under dynamic operation with 10 MHz toggling, self-heating stays within safe limits due to the low Cpd (40 pF) and efficient SOIC thermal path - confirming SN74HC682DW suitability for sealed or convection-cooled enclosures.