onsemi MC74LCX652DT

Overview

MC74LCX652DT from ON Semiconductor is a low-voltage CMOS octal transceiver/registered transceiver with dual enable, operating from 2.3 V to 3.6 V supply, featuring 5 V-tolerant inputs/outputs, 24 mA balanced output drive, and near-zero static supply current (10 μA). It serves as a bidirectional bus interface IC for memory address driving and TTL-level bus applications.

For engineers reviewing the MC74LCX652DT datasheet, pinout, applications, or equivalent options, key selection criteria include dual-clock register control (CAB/CBA), independent output enables (OEAB/OEBA), select multiplexing (SAB/SBA), 3-state non-inverting operation, and TSSOP-24 package compatibility with live insertion support.

Technical Context

The MC74LCX652DT implements two independent 8-bit data paths (A↔B) with edge-triggered clock registers on both sides, enabling synchronous storage of A or B bus data on LOW-to-HIGH transitions of CAB or CBA. Its dual-output-enable architecture allows independent control of A→B and B→A directions without affecting register clocking.

It supports three operational modes: real-time (transparent) transfer, registered transfer (with storage), and isolation mode - all selectable via OEAB, OEBA, SAB, and SBA. The 5 V-tolerant I/Os (VI up to 5.5 V) permit safe interfacing with legacy 5 V TTL systems while operating at 2.3–3.6 V core logic.

Key Specifications

Pinout & Package

MC74LCX652DT is housed in a 24-lead plastic TSSOP package (Case 948H), 4.4 mm wide, 0.65 mm pitch, with exposed pad not present. Pin layout supports standard PCB routing for high-density bus interfaces.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC823APWR and 74ALVC162245T, the MC74LCX652DT uniquely combines 5 V-tolerant I/O, dual-edge-triggered registers, and compact 24-pin TSSOP packaging - making it optimal for space-constrained, mixed-voltage bus bridging where synchronized data capture is required.

Availability

MC74LCX652DT is available at Aetrix Electronics and suitable for memory address driving, backplane bus interfacing, and hot-swappable module designs requiring stable component supply, long-term lifecycle assurance, and consistent parametric performance across temperature extremes.

Supply support for MC74LCX652DT 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

ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power management, analog, logic, and custom devices for automotive, industrial, and communications markets.

The MC74LCX652DT belongs to the LCX low-voltage CMOS logic family, designed specifically for high-speed, low-power bidirectional bus interfacing in mixed-voltage embedded systems where 5 V legacy compatibility and register-controlled data flow are critical.

FAQ

What is the maximum clock frequency supported by the MC74LCX652DT?

The MC74LCX652DT supports a maximum clock pulse frequency (f_max) of 150 MHz at V_CC = 3.0–3.6 V, as specified in its AC characteristics table. This rating applies to both CAB and CBA inputs under standard test conditions (C_L = 50 pF, R_L = 500 Ω). At V_CC = 2.7 V, the guaranteed f_max drops to 100 MHz. The MC74LCX652DT achieves this speed through optimized internal gate design and low propagation delays (as low as 1.5 ns).

Does the MC74LCX652DT require external pull-up resistors on its I/O pins?

No, the MC74LCX652DT does not require external pull-up resistors on its A0–A7 or B0–B7 pins under normal operation. Its inputs exhibit high-impedance TTL-compatible characteristics with VIH ≥ 2.0 V and VIL ≤ 0.8 V at V_CC ≥ 2.7 V, and its outputs actively drive HIGH/LOW states with ±24 mA capability. Pull-ups are unnecessary unless implementing open-bus arbitration or fail-safe idle states - which are outside the device's intended use case per the official ON Semiconductor datasheet for MC74LCX652DT.

Can the MC74LCX652DT operate with a 2.5 V supply voltage?

Yes, the MC74LCX652DT is fully rated for operation at 2.5 V supply voltage. Its recommended operating range is 2.3 V to 3.6 V, and all DC and AC specifications - including VIH/VIL thresholds, output drive strength (±12 mA min at V_CC = 2.7 V), and propagation delays - are guaranteed across this full range. At 2.5 V, the MC74LCX652DT maintains 5 V-tolerant inputs (VI up to 5.5 V) and meets LVTTL compatibility requirements, making it suitable for 2.5 V system integration.

How does the MC74LCX652DT handle simultaneous enable of OEAB and OEBA?

When both OEAB and OEBA are asserted LOW simultaneously, the MC74LCX652DT enters real-time (transparent) mode: A0–A7 directly drive B0–B7 and vice versa, bypassing internal registers. In this configuration, outputs reinforce their respective inputs - but data retention is not guaranteed per the datasheet truth table note. This mode is valid for bidirectional pass-through but should not be used for storage; for reliable register capture, OEAB and OEBA must be controlled independently per direction, and clocks (CAB/CBA) applied separately.

Is the MC74LCX652DT pin-compatible with the MC74LCX652DW variant?

Yes, the MC74LCX652DT and MC74LCX652DW share identical pin functions and electrical behavior, differing only in package type: DT is 24-lead TSSOP (Case 948H), while DW is 24-lead SOIC (Case 751E). Both have identical pin numbering, signal assignments (A0–A7, B0–B7, CAB, CBA, etc.), and thermal/electrical specifications. PCB layout must account for footprint differences - the TSSOP version has finer pitch (0.65 mm vs. 1.27 mm) and smaller body dimensions - but no netlist or schematic changes are required when substituting MC74LCX652DT for MC74LCX652DW.