NXP Semiconductors 74HCT652D,112

Overview

74HCT652D,112 from NXP Semiconductors (formerly Philips) is an octal bus transceiver/register with independent A/B bus registers, dual 3-state control (OEAB/OEBA), and real-time/storage mode selection via SAB/SBA inputs. It operates at 4.5 V to 5.5 V, delivers 92 MHz max clock frequency, supports 24-pin SO package, and is used in bidirectional data bus arbitration for microprocessor peripheral interfaces.

For engineers reviewing the 74HCT652D,112 datasheet, 74HCT652D,112 pinout, 74HCT652D,112 application, or 74HCT652D,112 equivalent, key selection criteria include independent A/B register storage, simultaneous A→B and B→A stored-data transfer capability, Schmitt-trigger clock inputs for noise immunity, and TTL-compatible input thresholds enabling direct interfacing with legacy LSTTL systems.

Technical Context

The 74HCT652D,112 integrates eight non-inverting transceiver channels with D-type flip-flops per bus direction, enabling concurrent storage of A-bus and B-bus data on separate clock edges (CPAB and CPBA). Its dual-select architecture (SAB/SBA) allows real-time pass-through or clock-gated register transfer without bus contention.

Schmitt-trigger inputs on CPAB and CPBA tolerate slow-rising clock signals, while OEAB and OEBA independently control output drivers for precise bus isolation. The device complies with JEDEC Standard No. 7A and achieves 13 ns typical propagation delay (An/Bn → Bn/An) at VCC = 5 V, CL = 15 pF.

Key Specifications

Pinout & Package

74HCT652D,112 is housed in a 24-pin Small Outline (SO) plastic package (SOT137A), with 1.27 mm pitch, surface-mount footprint, and standard JEDEC MS-013 compliance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74HCT652D,112, the 74HCT646D,112 offers reduced functionality for cost-constrained unidirectional buffering, while the SN74HCT652N provides identical electrical behavior in a through-hole package-making it a true form-fit-function alternative for legacy assembly.

Availability

74HCT652D,112 is available at Aetrix Electronics and suitable for microprocessor bus interfaces, memory-mapped peripheral connections, and FPGA-to-ASIC bridging requiring stable component supply and long-term industrial availability.

Supply support for 74HCT652D,112 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 leader specializing in secure connectivity solutions for automotive, industrial, and IoT applications, with roots in Philips' pioneering logic IC development.

The 74HCT652D,112 belongs to NXP's legacy 74HCT logic family, designed specifically for robust, pin-compatible upgrades of LSTTL systems requiring low-power CMOS performance and guaranteed TTL input compatibility.

FAQ

What is the primary function of the 74HCT652D,112 in a digital system?

The 74HCT652D,112 functions as an octal bidirectional bus transceiver with integrated A- and B-bus registers, enabling both real-time data pass-through and clock-synchronized storage. It supports independent control of data flow in either direction using dedicated select (SAB/SBA) and output enable (OEAB/OEBA) inputs, making it ideal for microprocessor bus arbitration and buffered peripheral interfacing where timing isolation is critical.

Does the 74HCT652D,112 support simultaneous transfer of stored data from A to B and B to A?

Yes, the 74HCT652D,112 uniquely supports concurrent A→B and B→A stored-data transfer - a feature distinguishing it from similar devices like the 74HCT646D,112. When OEAB and OEBA are both low and SAB/SBA are high, stored A-data appears on the B-bus while stored B-data appears on the A-bus in the same cycle, enabling full-duplex register exchange without additional logic.

What are the voltage-level requirements for TTL-compatible operation of the 74HCT652D,112?

The 74HCT652D,112 meets TTL input thresholds: VIH ≥ 2.0 V (min) and VIL ≤ 0.8 V (max) over VCC = 4.5 V to 5.5 V. This ensures direct interoperability with 74LS, 74ALS, and other LSTTL outputs without level shifters. Its outputs swing rail-to-rail (VOL ≤ 0.1 V, VOH ≥ 4.9 V at VCC = 5 V, IOH/IOL = ±4 mA), driving standard TTL loads.

How does the Schmitt-trigger action on CPAB and CPBA improve system reliability?

Schmitt-trigger inputs on CPAB and CPBA provide hysteresis (~0.5 V) that rejects noise and slow-rising/falling clock edges, preventing false triggering in electrically noisy environments or when using RC-generated clocks. This ensures deterministic register capture even with clock rise times up to 100 ns - a key advantage over non-hysteresis CMOS inputs in industrial control and legacy system upgrades.

Is the 74HCT652D,112 pin-compatible with the 74LS652 and 74HC652?

Yes, the 74HCT652D,112 is pin-compatible with both the 74LS652 (LSTTL) and 74HC652 (high-speed CMOS) families, sharing identical 24-pin SO (SOT137A) pinout and logic function. However, unlike the 74HC652, the 74HCT652D,112 features TTL-compatible inputs, and unlike the 74LS652, it offers significantly lower quiescent current and higher noise immunity - making it a direct drop-in upgrade.