NXP Semiconductors 74HC85PW,112

Overview

74HC85PW,112 from Nexperia (formerly Philips Semiconductors) is a 4-bit magnitude comparator IC used in digital logic systems to determine relative size of two binary words. It features A0–A3 and B0–B3 parallel inputs, three mutually exclusive outputs (QA>B, QA=B, QA<B), propagation delays as low as 11 ns (IA=B to QA=B at VCC = 4.5 V), and operates across 2.0–6.0 V supply range. It enables serial or parallel expansion for multi-bit comparisons in industrial control logic.

For engineers reviewing the 74HC85PW,112 datasheet, 74HC85PW,112 pinout, 74HC85PW,112 application, or 74HC85PW,112 equivalent, key selection considerations include cascading input/output compatibility (IA>B/IA=B/IA<B → QA>B/QA=B/QA<B), supply voltage tolerance (2.0–6.0 V), output drive capability (standard CMOS), and propagation delay performance across temperature and load conditions.

Technical Context

The 74HC85PW,112 implements combinational logic for unsigned 4-bit magnitude comparison using hierarchical feed-forward expansion architecture. Its internal design supports both serial cascading (daisy-chained via QA outputs to IA inputs) and parallel expansion without external gating, with mutually exclusive outputs under normal operation.

It conforms to JEDEC standard no. 7A and is pin-compatible with LSTTL. The device uses Si-gate CMOS technology, delivering rail-to-rail output swing and low static current, with defined input thresholds (VI = GND to VCC for HC) and specified dynamic power dissipation via CPD = 18 pF.

Key Specifications

Pinout & Package

TSSOP16 package (4.4 mm × 5.0 mm, 0.65 mm pitch), lead-free, RoHS-compliant, surface-mount.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 4-bit magnitude comparator applications.

Compared with SN74HC85DR and 74HCT85PW,118, the 74HC85PW,112 offers optimal thermal performance in space-constrained industrial PCBs due to its TSSOP16 package, while maintaining full functional equivalence with standard CMOS input thresholds - making it preferred for new designs targeting 3.3 V/5 V mixed-signal systems.

Availability

74HC85PW,112 is available at Aetrix Electronics and suitable for industrial process controllers, servo-motor position logic, digital test equipment, and legacy system emulation requiring stable component supply and long-term lifecycle support.

Supply support for 74HC85PW,112 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

Nexperia is a global semiconductor expert specializing in high-volume, high-reliability logic, analog, and discrete components, with roots in Philips Semiconductors' IC division.

The 74HC logic family - including the 74HC85PW,112 - was designed for robust, low-power, pin-compatible replacements of legacy TTL logic in industrial automation, instrumentation, and embedded control systems.

FAQ

What is the recommended power supply decoupling for 74HC85PW,112?

Place a 100 nF ceramic capacitor between VCC (pin 16) and GND (pin 8), located ≤5 mm from the package. For systems with multiple 74HC85PW,112 devices, add a 1–10 µF bulk capacitor per power rail segment. This suppresses switching noise and maintains stable logic thresholds during cascaded output transitions.

How do I configure 74HC85PW,112 for standalone 4-bit comparison without cascading?

For single-stage operation, tie IA<B (pin 2) and IA>B (pin 4) to GND, and IA=B (pin 3) to VCC. This initializes the expansion inputs to indicate equality of less-significant bits, enabling valid QA>B, QA=B, and QA<B outputs based solely on A0–A3 and B0–B3 inputs.

Does 74HC85PW,112 support 3.3 V operation?

Yes, 74HC85PW,112 is fully specified from 2.0 V to 6.0 V, including 3.3 V nominal supply. At VCC = 3.3 V, propagation delays increase moderately (e.g., An→QA=B typ. ~22 ns), but all logic functions, output drive, and cascading behavior remain guaranteed per datasheet limits across −40 °C to +125 °C.

Can 74HC85PW,112 be used to compare BCD-coded digits?

Yes - the 74HC85PW,112 performs unsigned binary magnitude comparison, which is valid for BCD since BCD digits (0–9) are monotonic subsets of 4-bit binary (0000–1001). No modification is needed; A0–A3 and B0–B3 accept BCD inputs directly, and QA>B/QA=B/QA<B reflect correct decimal digit relationships.

What is the maximum clock rate supported by 74HC85PW,112 in a cascaded 12-bit comparator?

The 74HC85PW,112 is combinational, not clocked - its speed depends on worst-case propagation through three stages. With tPHL/tPLH ≈ 24 ns per stage (An→QA=B at VCC = 4.5 V), total delay for 12-bit serial cascade is ~72 ns, supporting input update rates up to ~14 MHz. Parallel cascading reduces this to ~24 ns (single-stage delay).