NXP Semiconductors 74HC670N,652

Overview

74HC670N,652 from NXP Semiconductors is a 4 × 4-bit 3-state register file IC with independent read/write address inputs (RA/RB, WA/WB), dual enable controls (RE/WE), and true non-inverting outputs (Q0–Q3). It supports simultaneous read-from-one-location and write-to-another within a single clock cycle, operates at 2–6 V supply, and delivers 23 ns typical propagation delay (Dn→Qn) at 5 V. Used in early microprocessor data path buffering and ALU register staging.

For engineers reviewing the 74HC670N,652 datasheet, 74HC670N,652 pinout, 74HC670N,652 application, or 74HC670N,652 equivalent, key selection criteria include simultaneous read/write capability, 3-state bus driver output drive strength, 16-pin DIP package compatibility, and HCMOS-level input thresholds for TTL-interfaced systems.

Technical Context

The 74HC670N,652 implements a synchronous, address-decoded 4-word × 4-bit register file using Si-gate CMOS technology. Its dual-address architecture separates read (RA/RB) and write (WA/WB) paths, enabling concurrent access without arbitration logic. The RE and WE inputs operate asynchronously but are edge-agnostic-latching occurs on stable low levels, not transitions.

It features true 3-state outputs with high-impedance disable (Z-state) controlled solely by RE, independent of WE state. Internal latches retain data while WE is LOW, and read operations remain valid even during active writes to other addresses-no internal bus contention or timing interlock required.

Key Specifications

Pinout & Package

74HC670N,652 is supplied in a 16-pin plastic dual in-line package (DIP) with 0.3-inch body width and standard through-hole mounting. Pin pitch is 2.54 mm, and lead finish is tin-lead (SnPb).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar register file applications.

Compared with 74HC670N,652, the 74HCT670N,652 offers improved input compatibility with legacy TTL, while CD74HC670E provides identical functionality in a surface-mount package-neither is pin-compatible without layout changes, but both preserve functional equivalence in register-file-based architectures.

Availability

74HC670N,652 is available at Aetrix Electronics and suitable for microprocessor data path staging, ALU register interface, and industrial PLC I/O mapping requiring stable component supply and long-term obsolescence management.

Supply support for 74HC670N,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

NXP Semiconductors is a global semiconductor company formed from the spin-off of Philips' semiconductor division, specializing in secure connectivity solutions, automotive electronics, and logic ICs.

The 74HC/HCT670 belongs to NXP's legacy HC/HCT logic family-designed specifically for high-speed, low-power register file and data path applications in 8-bit and 16-bit embedded control systems.

FAQ

What is the maximum operating frequency of the 74HC670N,652?

The 74HC670N,652 does not specify a maximum clock frequency because it is an asynchronous register file-its speed is governed by propagation delays and setup/hold times. With 23 ns typical Dn→Qn delay at 5 V and 15 pF load, it supports reliable operation up to approximately 20 MHz in tightly timed systems, assuming adequate setup (12 ns) and hold (5 ns) margins for WE and address signals.

Can the 74HC670N,652 perform read and write operations in the same cycle?

Yes-the 74HC670N,652 supports true simultaneous read and write: while WE is LOW to write data to one address (selected by WA/WB), RE can be LOW to read from a different address (selected by RA/RB), with no internal conflict. This is enabled by physically separate read and write address decoders and independent latch paths.

Is the 74HC670N,652 pin-compatible with the 74LS670?

No-the 74HC670N,652 is not pin-compatible with the 74LS670. Although both are 4×4 register files, the 74LS670 uses a different pin assignment: its D0–D3 are on pins 1–4, whereas 74HC670N,652 places D0–D3 on pins 1,2,3,15. Direct replacement requires PCB redesign.

What happens to the outputs of the 74HC670N,652 when RE is HIGH?

When RE is HIGH, all four outputs (Q0–Q3) of the 74HC670N,652 enter a high-impedance (Z) state regardless of the state of WE, RA/RB, or data contents. This allows multiple 74HC670N,652 devices to share a common data bus without external tri-state logic.

Does the 74HC670N,652 require a clock signal to operate?

No-the 74HC670N,652 is fully asynchronous and requires no clock input. Data is latched on the address and enable signals: writing occurs when WE is LOW and WA/WB are stable; reading occurs when RE is LOW and RA/RB are stable. Timing is governed solely by propagation delays and setup/hold requirements.