Texas Instruments CD74HCT652M96

Overview

CD74HCT652M96 from Texas Instruments is a high-speed CMOS octal-bus transceiver/register with non-inverting three-state outputs, 24-pin SOIC package, -55°C to +125°C operating range, and 4.5V–5.5V supply voltage. It enables bidirectional data transfer between A and B buses with independent storage registers, real-time or stored data selection, and simultaneous bus isolation-used in industrial backplane interfaces and legacy system bus expansion.

For engineers reviewing the CD74HCT652M96 datasheet, CD74HCT652M96 pinout, CD74HCT652M96 application, or CD74HCT652M96 equivalent, key selection criteria include its HCT-level TTL-compatible inputs (VIH ≥ 2V, VIL ≤ 0.8V), 15 LSTTL load drive capability, 18ns typical propagation delay at 5V/15pF, three-state enable timing (tPZL/tPLZ ≤ 14ns), and dual-clock register control (CAB/CBA) for synchronized A/B bus latching.

Technical Context

The CD74HCT652M96 integrates eight identical bidirectional channels, each with D-type flip-flops, multiplexed real-time/stored data paths, and independent OEAB/OEBA three-state controls. Its select logic (SAB/SBA) eliminates decoding glitches during mode transitions by ensuring glitch-free switching between live bus data and registered outputs.

It operates strictly within 4.5V–5.5V, matching LSTTL input thresholds while delivering CMOS power efficiency. Clock inputs (CAB/CBA) are edge-triggered; low-to-high transitions store data regardless of SAB/SBA state, and staggered clocking is required when both registers are loaded under SAB=SBA=HIGH per functional table Note 3.

Key Specifications

Pinout & Package

CD74HCT652M96 uses a 24-pin SOIC (DW) package with standard 0.300-inch body width and 1.27mm pitch. Pin numbering follows JEDEC MS-013, with GND at pin 12 and VCC at pin 24.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ACT652N and 74ABT652PC, CD74HCT652M96 uniquely balances LSTTL compatibility, ultra-low quiescent current (160µA max), and full military-grade temperature range - making it irreplaceable in safety-critical embedded systems requiring long-term reliability under thermal stress.

Availability

CD74HCT652M96 is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy system bus expansion, military data acquisition hubs, aerospace avionics subsystems, and extended-temperature embedded controllers requiring stable component supply across long product lifecycles.

Supply support for CD74HCT652M96 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and logic solutions, with over 90 years of innovation in high-reliability components.

CD74HCT652M96 belongs to TI's legacy HC/HCT logic portfolio designed for robust, pin-compatible upgrades of obsolete TTL bus interface ICs in mission-critical industrial and defense systems.

FAQ

What is the maximum clock frequency supported by CD74HCT652M96 in register store mode?

The CD74HCT652M96 supports a maximum clock frequency of 17MHz at -55°C to +125°C when storing data into internal registers (CAB/CBA), as specified in the HCT switching characteristics table. This limit ensures setup/hold time compliance under worst-case temperature and voltage conditions, and applies regardless of whether SAB/SBA are HIGH or LOW. The 17MHz value reflects guaranteed operation-not typical performance-and must be used for timing closure in safety-certified designs.

Does CD74HCT652M96 support simultaneous real-time data transfer in both directions?

No, CD74HCT652M96 does not support true simultaneous bidirectional real-time transfer. Its functional table shows that real-time A→B transfer requires OEAB=L and OEBA=H, while real-time B→A requires OEAB=H and OEBA=L - mutually exclusive enable states. Simultaneous OEAB=L and OEBA=L enables stored-data transfer only (not real-time), and simultaneous OEAB=H and OEBA=H places both outputs in high-Z. Thus, real-time flow is strictly unidirectional per active cycle.

Can CD74HCT652M96 operate reliably at 4.2V supply voltage?

No, CD74HCT652M96 is not guaranteed to operate at 4.2V. Its HCT specification mandates a minimum VCC of 4.5V for full parameter compliance, including VIH ≥ 2.0V and VOL ≤ 0.4V. At 4.2V, input threshold margins degrade, propagation delay increases beyond spec, and three-state leakage may exceed ±5.0µA - violating datasheet limits. Systems requiring <4.5V operation should use the HC variant (CD74HC652) instead.

What is the purpose of the "staggered clocking" requirement noted in the CD74HCT652M96 datasheet?

The staggered clocking requirement (functional table Note 3) applies only when SAB=SBA=HIGH and both registers must be loaded simultaneously. In this mode, CAB and CBA must not transition on the same clock edge to prevent metastability in internal select logic. Staggering ensures one register captures data before the other begins sampling, maintaining deterministic register state. When SAB or SBA is LOW, clocks may be concurrent without restriction.

Is CD74HCT652M96 still recommended for new designs despite its OBSOLETE status on TI's website?

Although TI lists CD74HCT652M96 as OBSOLETE in its packaging addendum, Aetrix Electronics maintains active inventory and full traceable supply chain support for this part. Its technical specifications remain fully validated, and it continues to serve in long-lifecycle industrial, defense, and aerospace programs where form-fit-function replacement is prohibited. Customers receive full documentation, lot traceability, and obsolescence mitigation planning - confirming CD74HCT652M96 as a viable solution for sustaining engineering.