onsemi MC74ACT652NG

Overview

MC74ACT652NG from onsemi is an octal registered bus transceiver with non-inverting 3-state outputs, designed for bidirectional data flow control between two 8-bit buses (A and B). It supports real-time and registered data transfer modes, features TTL-compatible inputs, delivers ±24 mA output drive, and operates at 4.5–5.5 V supply - used in industrial backplane interface and legacy system bus expansion.

For engineers reviewing the MC74ACT652NG datasheet, pinout, applications, or equivalent options, this page provides verified functional roles, timing-critical AC/DC specs, SOIC-24 package details, and validated alternative options for bus interface redesigns requiring register-controlled data multiplexing.

Technical Context

The MC74ACT652NG integrates dual independent D-type flip-flop registers per bus (A0–A7 and B0–B7), enabling simultaneous storage of A- and B-bus data on LOW-to-HIGH clock transitions at CAB or CBA. Its logic supports four distinct data-handling functions: real-time A→B/B→A transfer, register-to-bus output, and bus-to-register capture.

Control is managed via three dedicated signal groups per direction: transmit/receive select (SAB/SBA), output enable (GAB/GBA), and clock (CAB/CBA). All outputs are 3-state capable, with TTL-compatible input thresholds (VIH = 2.0 V min, VIL = 0.8 V max at VCC = 5.5 V) and guaranteed propagation delays ≤16.5 ns (tPHL/tPLH) under 50 pF load at 5 V.

Key Specifications

Pinout & Package

MC74ACT652NG uses a 24-pin SOIC wide-body (SOIC-24, Case 751E) package with 15.25 mm × 7.5 mm body dimensions, 1.27 mm pitch, and Pb-free (G-suffix) construction.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal registered transceiver applications.

Compared with SN74ACT652N and MC74ACT646NG, the MC74ACT652NG uniquely combines non-inverting 3-state operation, SOIC-24 packaging, and 59.8°C/W thermal resistance - making it optimal for space-constrained, thermally managed industrial PCBs requiring direct TTL compatibility and register-controlled bus arbitration.

Availability

MC74ACT652NG is available at Aetrix Electronics and suitable for industrial backplane interface, legacy system bus expansion, and embedded diagnostic subsystems requiring stable component supply across extended temperature ranges (−40°C to +85°C) and long-lifecycle programs.

Supply support for MC74ACT652NG 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient silicon solutions for automotive, industrial, cloud, and IoT applications.

The MC74ACT652NG belongs to the 74ACT advanced CMOS logic family, engineered for high-speed, low-power bus interface applications in industrial control and legacy system upgrades where TTL compatibility and register-controlled data flow are essential.

FAQ

What is the maximum operating frequency supported by the MC74ACT652NG?

The MC74ACT652NG does not specify a maximum clock frequency in its datasheet, but its worst-case propagation delay is 16.5 ns (tPLH/tPHL at TA = −40°C to +85°C, CL = 50 pF, VCC = 5.5 V). This supports reliable operation up to approximately 30 MHz in synchronous bus applications where setup/hold timing margins are maintained. The MC74ACT652NG's actual usable frequency depends on system-level loading, PCB trace length, and clock edge monotonicity.

Does the MC74ACT652NG support mixed-voltage operation (e.g., 3.3 V inputs with 5 V supply)?

No, the MC74ACT652NG is not designed for mixed-voltage operation. Its input voltage range is specified as 0 V to VCC, and VIH/VIL thresholds are defined relative to VCC (e.g., VIH ≥ 2.0 V at VCC = 5.5 V). Applying 3.3 V logic signals to a 5 V-powered MC74ACT652NG may result in marginal or non-functional HIGH-level recognition. For 3.3 V ↔ 5 V interfacing, external level translators or a 3.3 V–compatible transceiver like the 74LVC652 should be used instead of relying on the MC74ACT652NG.

Can the MC74ACT652NG be used without connecting both VCC and GND pins?

No - the MC74ACT652NG requires both VCC (Pin 24) and GND (Pin 12) to be properly connected to their respective supply rails for correct operation. Leaving either unconnected will prevent internal logic from powering up, disable register functionality, and cause undefined output states. Decoupling capacitors (0.1 μF ceramic) must be placed within 10 mm of Pin 24 and Pin 12 to suppress switching noise and ensure stable timing performance across temperature and load conditions.

How does the MC74ACT652NG handle bus contention during direction switching?

The MC74ACT652NG prevents bus contention through independent 3-state control via GAB and GBA pins. When changing direction (e.g., from A→B to B→A), designers must assert both GAB and GBA to high (disabled) briefly before enabling the new direction - ensuring outputs enter high-impedance state simultaneously. The MC74ACT652NG's tPZH/tPLZ (1.5–13.0 ns) and tPHZ/tPLZ (2.5–14.0 ns) guarantee fast, predictable disable timing, minimizing overlap windows where both sides could drive the bus.

Is the MC74ACT652NG pin-compatible with the older MC74AC652NG variant?

Yes - the MC74ACT652NG and MC74AC652NG share identical pinout, package (SOIC-24), and functional block diagram. However, they differ electrically: the MC74ACT652NG has TTL-compatible inputs (VIH = 2.0 V min), while the MC74AC652NG requires CMOS-level inputs (VIH = 3.15 V min at VCC = 4.5 V). Substituting MC74ACT652NG for MC74AC652NG is safe in TTL-driven systems; substituting the reverse risks input threshold violations and unreliable operation.