NXP Semiconductors 74ABT657DB,118

Overview

74ABT657DB,118 from NXP Semiconductors is an octal bidirectional transceiver with integrated 8-bit parity generator/checker and 3-state outputs, designed for high-speed bus interfacing in industrial control and data communication systems. It delivers ±32 mA HIGH-level and 64 mA LOW-level output drive, operates from 4.5 V to 5.5 V, and supports transmit/receive direction control via T/R pin with parity selection via ODD/EVEN pin.

For engineers reviewing the 74ABT657DB,118 datasheet, 74ABT657DB,118 pinout, 74ABT657DB,118 application, or 74ABT657DB,118 equivalent, this device is selected for synchronous parallel bus systems requiring real-time parity validation, robust noise immunity, and high-current drive capability on A/B ports without external logic.

Technical Context

The 74ABT657DB,118 implements a BiCMOS architecture enabling simultaneous low static power (≤250 µA supply current in disabled state) and high-speed operation (typical tPLH/tPHL ≤ 3 ns for A↔B paths). Its parity engine performs real-time even/odd parity generation during transmit mode and full-bit parity checking during receive mode, with ERROR output asserting only when mismatched parity is detected.

Direction control is strictly determined by the T/R input: HIGH enables A→B data flow with PARITY as output; LOW enables B→A flow with PARITY as input and ERROR as active-HIGH fault indicator. Output Enable (OE, active LOW) forces all I/O pins into high-impedance state independently of T/R, supporting bus arbitration and hot-swap compatibility.

Key Specifications

Pinout & Package

74ABT657DB,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 while maintaining mechanical robustness and thermal performance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal transceiver with parity applications.

Compared with 74ABT657DB,118, the 74LVT657PW,118 trades 5 V compatibility and higher drive for lower voltage operation and marginal speed gain, while SN74ABT657N retains full functional equivalence but sacrifices modern packaging density and thermal performance.

Availability

74ABT657DB,118 is available at Aetrix Electronics and suitable for industrial PLC backplanes, telecom line card interconnects, and automotive ECU diagnostics requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for 74ABT657DB,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 company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and IoT applications.

The 74ABT657DB,118 belongs to NXP's ABT-series advanced bus-interface logic family, engineered for high-speed, low-power, and high-noise-immunity parallel bus systems in mission-critical industrial and communications equipment.

FAQ

What is the function of the ODD/EVEN pin on the 74ABT657DB,118?

The ODD/EVEN pin on the 74ABT657DB,118 configures the parity generator/checker to produce or validate either odd or even parity. When LOW, it enables even-parity operation: during transmit (T/R = HIGH), PARITY output reflects even parity of A-port inputs; during receive (T/R = LOW), ERROR asserts if B-port inputs plus PARITY input yield odd total bit count. This pin directly determines system-level error detection behavior without firmware intervention.

How does the 74ABT657DB,118 handle bus contention during power-up?

The 74ABT657DB,118 features inherent power-up 3-state functionality: all A-port, B-port, PARITY, and ERROR outputs remain in high-impedance state until VCC reaches valid operating range and OE is actively driven LOW. This prevents unintended bus loading or signal conflicts at power-on, eliminating need for external reset sequencing or pull-up/pull-down networks on control pins.

Can the 74ABT657DB,118 operate reliably at 4.5 V supply?

Yes, the 74ABT657DB,118 is fully specified for operation at 4.5 V minimum supply voltage per Table 5 (Recommended Operating Conditions). At VCC = 4.5 V, it maintains guaranteed 64 mA LOW-level output drive, ≤4.6 ns A↔B propagation delay across −40 °C to +85 °C, and valid VIH/VIL thresholds - making it suitable for brown-out tolerant industrial systems where rail regulation may dip near 4.5 V.

What is the maximum capacitive load the 74ABT657DB,118 can drive on its B-port outputs?

The 74ABT657DB,118 is characterized for dynamic performance up to 50 pF load capacitance (per Table 8 test conditions), with propagation delays measured under CL = 50 pF and RL = 500 Ω. While it can physically drive higher capacitance, timing margins degrade beyond this value; for loads >50 pF, derating of maximum operating frequency or addition of series termination is recommended to maintain signal integrity.

Is the ERROR output of the 74ABT657DB,118 actively driven or open-drain?

The ERROR output of the 74ABT657DB,118 is actively driven push-pull: it sources current in HIGH state and sinks current in LOW state, with no internal pull-up or open-drain structure. Per Table 6, IOH = −32 mA and IOL = 64 mA are specified, confirming full rail-to-rail active drive capability - enabling direct connection to FPGA interrupt inputs or microcontroller GPIOs without external pull-up resistors.