onsemi 74LCX652MTC

Overview

74LCX652MTC from ON Semiconductor is an octal bus transceiver/register with dual D-type flip-flops, 5V-tolerant I/Os, and independent A/B bus control logic. It operates at 2.3–3.6 V V_CC, delivers 7.0 ns max propagation delay at 3.3 V, supports ±24 mA output drive, and enables real-time or registered data transfer between 8-bit buses in mixed-voltage systems such as 3.3 V CPU-to-5 V peripheral interfaces.

For engineers reviewing the 74LCX652MTC datasheet, pinout, applications, or equivalent options, key selection criteria include 5V-tolerant I/O compatibility, dual-clock register control (CPAB/CPBA), independent OEAB/OEBA enable logic, and TSSOP-24 packaging for high-density board layouts.

Technical Context

The 74LCX652MTC implements two independent 8-bit bidirectional transceivers, each with dedicated clock (CPAB/CPBA), select (SAB/SBA), and output-enable (OEAB/OEBA) inputs. Its internal D-flip-flops allow synchronous latching of A- or B-bus data on LOW-to-HIGH clock transitions, regardless of OE state - enabling simultaneous storage and real-time pass-through modes.

It uses advanced CMOS process to achieve 150 MHz max clock frequency with 25 pF power dissipation capacitance, while maintaining 10 µA max ICC quiescent current. The device features patented noise/EMI reduction circuitry, live-insertion support via power-down high-impedance I/Os, and latch-up immunity exceeding 500 mA.

Key Specifications

Pinout & Package

74LCX652MTC is housed in a 24-lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153 compliant, 4.4 mm wide, with 0.65 mm lead pitch and exposed pad not present. Pin 1 marked by notch or dot; pin count follows standard counter-clockwise numbering.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74LCX652MTC, both alternatives lack integrated D-flip-flop registers and independent clock/select logic, making them unsuitable for applications requiring deterministic data capture, dual-clock domain synchronization, or stored-data multiplexing between buses.

Availability

74LCX652MTC is available at Aetrix Electronics and suitable for industrial PLC backplanes, FPGA-to-microcontroller bridges, memory-mapped I/O expansion, and hot-swappable module communication requiring stable component supply and long-term lifecycle assurance.

Supply support for 74LCX652MTC 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, cloud, and consumer markets.

The 74LCX family was designed for low-voltage, high-speed mixed-signal interfacing - specifically targeting 2.5 V/3.3 V systems needing robust 5 V bus compatibility without external translation circuitry.

FAQ

What is the maximum clock frequency supported by the 74LCX652MTC?

The 74LCX652MTC supports a maximum clock frequency of 150 MHz under recommended operating conditions (V_CC = 3.3 V, T_A = −40°C to +85°C, C_L = 50 pF). This rating applies to both CPAB and CPBA inputs independently, enabling high-throughput data registration in time-critical bus arbitration systems. The 74LCX652MTC achieves this performance while maintaining sub-7 ns propagation delay and low dynamic power consumption.

Does the 74LCX652MTC require external pull-up resistors on its OE or clock inputs?

No external pull-up resistors are required on OEAB, OEBA, CPAB, or CPBA for normal operation - all control inputs are CMOS-compatible with rail-to-rail logic thresholds. However, per Fairchild Application Note DS011998 Note 1, if OE is left unconnected during power-up/down, a pull-up resistor to V_CC is recommended to ensure outputs remain in high-impedance state until firmware initializes control logic. The 74LCX652MTC itself does not mandate this resistor for functional correctness during active operation.

Can the 74LCX652MTC operate with a 2.5 V supply and still interface safely with 5 V signals?

Yes - the 74LCX652MTC is fully specified for 2.3 V to 3.6 V V_CC, and its inputs/outputs are rated for 0 V to 5.5 V regardless of supply voltage. At V_CC = 2.5 V, it maintains 5 V tolerance on all I/O pins, supports ±8 mA output drive, and meets AC timing specs including 8.4 ns max t_PLH/t_PHL. This makes the 74LCX652MTC ideal for 2.5 V core logic interfacing with 5 V peripherals without level-shifting components.

How does the 74LCX652MTC handle simultaneous real-time and registered data transfer?

The 74LCX652MTC supports concurrent real-time and registered transfer via independent SAB/SBA select inputs and OEAB/OEBA enables. For example, setting SAB = LOW and SBA = HIGH routes real-time A-bus data to B-bus while routing stored B-bus data to A-bus - all without conflict. This mode relies on the 74LCX652MTC's dual-register architecture and asynchronous clock inputs (CPAB/CPBA), enabling flexible bus arbitration in multi-master systems.

Is the 74LCX652MTC pin-compatible with other LCX-series transceivers like the 74LCX162245?

No - the 74LCX652MTC is not pin-compatible with the 74LCX162245 or any other LCX transceiver. It uses a unique 24-pin TSSOP (MTC24) footprint with dedicated CPAB, CPBA, SAB, SBA, OEAB, and OEBA control pins not found on 16-bit or non-registering variants. Pin mapping, function allocation, and internal logic architecture differ fundamentally; PCB layout must be designed specifically for the 74LCX652MTC.