NXP Semiconductors 74ABT899A,623

Overview

74ABT899A,623 from NXP Semiconductors (formerly Philips) is a 9-bit dual-latch transceiver with integrated 8-bit parity generator/checker and 3-State outputs. It supports bidirectional A↔B data flow, selectable ODD/EVEN parity, independent latch enables (LEA/LEB), and real-time parity error detection via ERRA/ERRB outputs. Used in high-reliability bus interfaces requiring concurrent parity generation and verification.

For engineers reviewing the 74ABT899A,623 datasheet, 74ABT899A,623 pinout, 74ABT899A,623 application, or 74ABT899A,623 equivalent, key selection criteria include its 28-pin PLCC package, ±32 mA/±64 mA drive capability, sub-5 ns propagation delay (An→Bn), live insertion support, and simultaneous A/B bus latching with parity feed-through or generation modes.

Technical Context

The 74ABT899A,623 implements two independent transparent latches-one per bus-with separate LEA and LEB controls enabling flexible timing for A-to-B and B-to-A transfers. Its parity logic operates continuously on latched data, generating APAR/BPAR outputs and asserting active-low ERRA/ERRB when parity mismatches occur on either bus-even while outputs are in 3-State.

Three operational modes-transparent latch + generate parity, transparent latch + feed-through parity, and latched input + parity control-are selected via SEL (generate/feed-through) and ODD/EVEN (parity type). All modes apply identically to both directions, ensuring symmetrical A/B functionality as confirmed in the functional description and mode table.

Key Specifications

Pinout & Package

74ABT899A,623 is housed in a 28-pin Plastic Leaded Chip Carrier (PLCC) package (SOT261-3), with gull-wing leads and a 1.27 mm pitch. The package is lead-free compatible and rated for reflow soldering per JEDEC J-STD-020.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 9-bit parity transceiver applications.

Compared with 74ABT899A,623, the 74FCT899ATQG offers reduced power and higher speed but sacrifices robustness for hot-swap environments, while the SN74ABT899N matches electrical behavior exactly but requires PCB redesign due to package incompatibility.

Availability

74ABT899A,623 is available at Aetrix Electronics and suitable for industrial backplane interfaces, military data link controllers, telecom line card data paths, and test equipment digital I/O modules requiring stable component supply across extended product lifecycles.

Supply support for 74ABT899A,623 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 focused on secure connectivity solutions for automotive, industrial, and IoT applications, with roots in Philips' pioneering logic IC development.

The 74ABT series was designed for high-speed, low-noise 5 V TTL-compatible applications demanding robust drive strength, fast propagation, and advanced bus management features like parity checking and live insertion.

FAQ

What is the function of the SEL pin on the 74ABT899A,623?

The SEL (Mode Select) pin on the 74ABT899A,623 determines whether parity is generated or fed through. When SEL = Low, the device generates new parity bits (APAR/BPAR) from A0–A7 or B0–B7 data; when SEL = High, it passes the incoming parity bit unchanged. This enables flexible integration into systems that either require dynamic parity generation or must preserve existing parity values - a capability explicitly defined in the Functional Description and verified in the Function Table.

Does the 74ABT899A,623 support live insertion, and what does that mean for system design?

Yes, the 74ABT899A,623 supports live insertion/extraction as confirmed in its Features list and Absolute Maximum Ratings. This means the device can be safely inserted into or removed from a powered-backplane system without causing latch-up or permanent damage. Its design exceeds 500 mA latch-up immunity per JEDEC JC40.2, allowing hot-swap-capable modular architectures - a critical requirement for telecom and military systems where maintenance must occur without system shutdown.

How does the 74ABT899A,623 handle power-up sequencing, and why is this important?

The 74ABT899A,623 incorporates power-up 3-State and power-up reset functionality, ensuring all outputs remain in high-impedance until VCC stabilizes and internal states settle. This prevents bus contention during power ramp-up - a common failure mode in multi-device 5 V systems. Verified in DC Electrical Characteristics (VRST parameter) and explicitly called out in Features, this behavior eliminates the need for external reset circuitry in most applications using the 74ABT899A,623.

Can the 74ABT899A,623 simultaneously generate and check parity on both buses?

Yes, the 74ABT899A,623 can simultaneously generate and check parity on both A and B buses, as stated in its Features and confirmed by the PARITY AND ERROR FUNCTION TABLE. When SEL = Low and both LEA and LEB are High, it generates APAR from A0–A7 and BPAR from B0–B7 while continuously comparing each against the corresponding bus's latched data - asserting ERRA or ERRB if a mismatch occurs. This concurrent operation is fundamental to its role in fault-tolerant bus architectures.

What package type is used for the 74ABT899A,623, and is it RoHS-compliant?

The 74ABT899A,623 uses a 28-pin Plastic Leaded Chip Carrier (PLCC) package, identified as SOT261-3 in Philips/NXP documentation. While the original 1998 datasheet predates RoHS, current production versions supplied by NXP and authorized distributors meet RoHS Directive 2011/65/EU and are lead-free. Aetrix Electronics provides full material declarations and compliance documentation for the 74ABT899A,623 upon request.