NXP Semiconductors 74ABT646ADB,118

Overview

74ABT646ADB,118 from NXP Semiconductors is an octal bus transceiver/register with 3-state outputs, combining bidirectional data routing and dual independent register storage in a single SSOP24 package. It supports real-time or registered A↔B bus transfer, features ±64 mA/−32 mA output drive, operates from 4.5 V to 5.5 V, and delivers propagation delays as low as 1.5 ns for critical timing paths in industrial control backplanes.

For engineers reviewing the 74ABT646ADB,118 datasheet, 74ABT646ADB,118 pinout, 74ABT646ADB,118 application, or 74ABT646ADB,118 equivalent, key selection criteria include its dual-clock (CPAB/CPBA) register control, DIR/OE/SAB/SBA multiplexed mode selection, live insertion capability, and latch-up immunity exceeding 500 mA per JESD78B Class II.

Technical Context

The 74ABT646ADB,118 implements a BiCMOS architecture enabling simultaneous high-speed switching (f_max = 350 MHz) and robust DC drive (I_OL = 64 mA, I_OH = −32 mA). Its functional core integrates two independent 8-bit D-type flip-flop registers-one per bus-with asynchronous 3-state control via OE and direction arbitration via DIR.

Mode selection is governed by four dedicated control inputs: SAB and SBA determine whether data flows in real time or is latched from A→B or B→A; CPAB and CPBA provide edge-triggered clocking into respective registers. All control pins accept standard TTL-level thresholds (V_IL ≤ 0.8 V, V_IH ≥ 2.0 V) across −40 °C to +85 °C.

Key Specifications

Pinout & Package

74ABT646ADB,118 is housed in a plastic shrink small outline package (SSOP24) with 24 leads, body width 5.3 mm (SOT340-1), optimized for high-density PCB layouts and automated surface-mount assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74ABT646AD,118 and SN74ABT646DBR, the 74ABT646ADB,118 provides the highest maximum clock frequency (350 MHz) and lowest propagation delay (1.5 ns min), making it optimal for high-speed industrial backplanes where timing closure is constrained.

Availability

74ABT646ADB,118 is available at Aetrix Electronics and suitable for industrial backplane interfaces, automotive body control modules, automated test equipment signal routing, and programmable logic controller I/O expansion requiring stable component supply across extended temperature ranges.

Supply support for 74ABT646ADB,118 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 over 50 years of analog and logic IC heritage.

The 74ABT646ADB,118 belongs to NXP's ABT-series advanced BiCMOS logic family, engineered specifically for high-speed, high-drive 5 V bus interfacing in noise-immune industrial and automotive control systems.

FAQ

What is the primary function of the 74ABT646ADB,118 in a system design?

The 74ABT646ADB,118 serves as an octal bidirectional bus transceiver with integrated dual 8-bit registers, enabling real-time or clocked data transfer between two 8-bit buses (A and B). Its DIR, OE, SAB, and SBA inputs allow dynamic configuration of direction, output enable, and register bypass-making it ideal for protocol bridging and buffered I/O expansion. The 74ABT646ADB,118 eliminates the need for separate transceivers and latches in space-constrained designs.

Does the 74ABT646ADB,118 support hot-swap or live insertion?

Yes, the 74ABT646ADB,118 supports live insertion and extraction due to its power-up 3-state feature and controlled I/O leakage current (≤±100 µA). During power ramp-up, outputs remain in high-impedance until VCC stabilizes, preventing bus contention. This behavior is validated per NXP's product data sheet Rev. 03 and enables safe module replacement in backplane systems without powering down the entire chassis. The 74ABT646ADB,118 maintains this capability across its full −40 °C to +85 °C operating range.

What are the absolute maximum ratings for supply voltage and junction temperature of the 74ABT646ADB,118?

The 74ABT646ADB,118 has an absolute maximum supply voltage (V_CC) of −0.5 V to +7.0 V and a maximum junction temperature (T_j) of 150 °C, as specified in Table 4 of the NXP datasheet. These limits define stress conditions beyond which permanent device damage may occur. For reliable operation, the recommended V_CC range is strictly 4.5 V to 5.5 V, and continuous operation must maintain T_j ≤ 150 °C-requiring appropriate PCB copper area and airflow in high-power applications. The 74ABT646ADB,118 thermal performance is characterized for its SSOP24 (SOT340-1) package.

How does the 74ABT646ADB,118 handle simultaneous register loading from both A and B buses?

The 74ABT646ADB,118 supports concurrent register loading: asserting CPAB HIGH captures data from the A bus into the B-side registers, while asserting CPBA HIGH captures data from the B bus into the A-side registers. Both clocks can be asserted simultaneously-enabling full 16-bit bidirectional snapshot capture. This behavior is explicitly defined in Table 3 (Function Table) and Figure 5 ("Storage from A, B, or A and B") of the NXP datasheet. The 74ABT646ADB,118 maintains independent register states regardless of OE or DIR state during clock transitions.

What is the significance of the SAB and SBA pins on the 74ABT646ADB,118?

The SAB (Select A-to-B) and SBA (Select B-to-A) pins on the 74ABT646ADB,118 determine whether data transfers in real time or from internal registers. When SAB is HIGH and DIR is HIGH, stored A-bus data is driven onto the B bus; when SBA is HIGH and DIR is LOW, stored B-bus data is driven onto the A bus. These pins decouple data routing logic from clocking-allowing flexible buffering strategies without altering clock timing. The 74ABT646ADB,118 uses these inputs to implement the four fundamental bus management functions shown in Figure 5 of its datasheet.