NXP Semiconductors 74HCT147D,652

Overview

74HCT147D,652 from Nexperia (formerly Philips Semiconductors) is a 10-to-4 line priority encoder IC that converts nine active-LOW decimal inputs (A0–A8) into four active-LOW BCD outputs (Y0–Y3), with A8 assigned highest priority. It operates at 4.5 V supply, delivers 44 ns typical propagation delay, and supports industrial temperature range (−40 °C to +85 °C) for switch encoding in panel control systems.

For engineers reviewing the 74HCT147D,652 datasheet, 74HCT147D,652 pinout, 74HCT147D,652 application, or 74HCT147D,652 equivalent, key selection criteria include active-LOW input/output logic polarity, priority encoding behavior under multiple simultaneous inputs, BCD output compatibility with downstream TTL/CMOS decoders, and SO16 package footprint constraints.

Technical Context

The 74HCT147D,652 implements priority encoding using standard CMOS logic with TTL-compatible input thresholds (VI = GND to 3 V), enabling direct interfacing with legacy LSTTL systems. Its functional behavior relies on implied decimal "zero" encoding-when all nine inputs are HIGH, all four outputs go HIGH to represent '0'.

Propagation delay (tPHL/tPLH = 44 ns typ. at VCC = 4.5 V, CL = 50 pF) and output transition time (tTHL/tTLH = 19 ns typ.) are characterized across −40 °C to +85 °C, confirming stable timing performance in industrial control environments without external buffering.

Key Specifications

Pinout & Package

74HCT147D,652 is supplied in a 16-pin small outline package (SO16), with 1.27 mm pitch, body width 3.9 mm, and JEDEC MS-012AC compliant outline.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LS147N and 74HC147D,653, the 74HCT147D,652 uniquely balances TTL input compatibility, 5 V system integration, and moderate power consumption - making it optimal for industrial encoders where robustness and interoperability supersede raw speed or ultra-low voltage operation.

Availability

74HCT147D,652 is available at Aetrix Electronics and suitable for industrial control panels, test equipment interfaces, and embedded keypad subsystems requiring stable component supply and long-term manufacturability.

Supply support for 74HCT147D,652 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 delivering high-performance, reliable logic, analog, and discrete components with focus on efficiency and sustainability.

The 74HCT147D,652 belongs to Nexperia's 74HCT logic family, engineered for seamless migration from legacy TTL systems while maintaining CMOS power advantages in industrial and automotive-qualified applications.

FAQ

What is the input logic polarity of the 74HCT147D,652?

The 74HCT147D,652 features active-LOW inputs (A0–A8): a logic LOW asserts that input line. This polarity allows direct connection to grounded mechanical switches or open-collector drivers. All nine inputs must be HIGH to encode decimal '0', resulting in all four outputs (Y0–Y3) going HIGH. The 74HCT147D,652 does not accept active-HIGH decimal inputs without external inversion.

Does the 74HCT147D,652 support true 10-line encoding including digit '0'?

Yes - the 74HCT147D,652 implements implied zero encoding: when all nine inputs (A0–A8) are HIGH, outputs Y3–Y0 all go HIGH to represent decimal '0'. This eliminates the need for a dedicated tenth input or external logic to detect the zero state. The 74HCT147D,652 thus fully supports 0–9 decimal encoding using only nine physical inputs.

Can the 74HCT147D,652 be used with a 3.3 V supply?

No - the 74HCT147D,652 is specified only for 4.5 V to 5.5 V operation. Its TTL-compatible input thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V) and internal gate design require minimum 4.5 V for guaranteed DC and AC performance across temperature. Using 3.3 V risks incorrect logic recognition and timing violations. For 3.3 V systems, consider the 74LVC147 or similar LVCMOS alternatives instead of the 74HCT147D,652.

What is the meaning of the 'n.c.' pin on the 74HCT147D,652?

Pin 15 of the 74HCT147D,652 is marked 'n.c.' (no connection), indicating no internal silicon connection. It must remain unconnected - neither tied to VCC, GND, nor routed on PCB. Soldering or wiring to this pin may cause mechanical stress or unintended coupling. The 74HCT147D,652 functions correctly with pin 15 floating, as confirmed in Philips/Nexperia's official package outlines and functional diagrams.

How does priority encoding work when multiple inputs are active on the 74HCT147D,652?

When two or more inputs (A0–A8) are simultaneously LOW, the 74HCT147D,652 encodes only the highest-priority input: A8 > A7 > … > A0. For example, if A2 and A5 are both LOW, output reflects A5 (binary 0101). Lower-priority inputs are ignored - no arbitration logic or additional circuitry is needed. This deterministic behavior is hardwired in the 74HCT147D,652's logic diagram and verified in its function table.