NXP Semiconductors 74HC640DB,112

Overview

74HC640DB,112 from NXP Semiconductors (formerly Philips) is an octal inverting bus transceiver with 3-state outputs, designed for bidirectional data flow control between two 8-bit buses. It features direction control (DIR), active-low output enable (OE), propagation delay of 9 ns at VCC = 5 V, and operates across −40 °C to +125 °C. It is used in industrial backplane interfaces requiring bus isolation and level translation.

For engineers reviewing the 74HC640DB,112 datasheet, 74HC640DB,112 pinout, 74HC640DB,112 application, or 74HC640DB,112 equivalent, key selection criteria include its inverting logic behavior, 3-state timing (tPZH/tPHZ ≤ 45 ns), bus driver output capability, and compatibility with LSTTL input thresholds in HCT mode.

Technical Context

The 74HC640DB,112 implements dual-directional data transfer using a single DIR pin to select A→B (inverting) or B→A (inverting) paths, with OE enabling/disabling all outputs simultaneously into high-impedance state. Its CMOS silicon-gate process ensures low static current and rail-to-rail voltage operation from 2.0 V to 6.0 V.

Unlike non-inverting transceivers (e.g., 74HC245), the 74HC640DB,112 inverts data on both transmit and receive paths - a fixed functional trait confirmed in the function table and functional diagram. All 16 I/O pins (A0–A7, B0–B7) are fully symmetrical and support bus driving per JEDEC standard no. 7A.

Key Specifications

Pinout & Package

74HC640DB,112 is housed in a 20-pin SO20 (Small Outline) package per JEDEC MS-013, with 0.60 mm lead pitch and body size 12.8 mm × 7.5 mm. Pin 10 is GND; Pin 20 is VCC; DIR (Pin 1) and OE (Pin 19) are active-low control inputs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74HC640DB,112, the 74HCT640DB,112 improves noise margin in mixed-logic systems, while the SN74HC640N trades miniaturization and high-frequency performance for mechanical robustness and ease of manual assembly - neither is pin-compatible due to differing package types.

Availability

74HC640DB,112 is available at Aetrix Electronics and suitable for industrial backplane interfaces, automotive ECU data multiplexing, and test equipment signal routing requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for 74HC640DB,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 focused on secure connectivity solutions for automotive, industrial, and IoT applications, with roots in Philips' pioneering logic IC development.

The 74HC640DB,112 belongs to NXP's legacy 74HC/HCT logic family - engineered for drop-in replacement of bipolar TTL in cost-sensitive, high-reliability embedded systems where power efficiency and wide voltage operation are critical.

FAQ

What is the logic behavior of the 74HC640DB,112 during data transfer?

The 74HC640DB,112 inverts data on both A→B and B→A paths regardless of DIR state. When DIR = LOW, A0–A7 drive inverted values onto B0–B7; when DIR = HIGH, B0–B7 drive inverted values onto A0–A7. This fixed inversion is intrinsic to the device architecture and cannot be disabled.

Does the 74HC640DB,112 support 3.3 V operation?

Yes, the 74HC640DB,112 operates reliably from 2.0 V to 6.0 V. At VCC = 3.3 V, propagation delay increases to ~15 ns (typical), and output drive strength reduces to ±4.2 mA, but all DC and AC specifications remain valid per the 74HC family datasheet - making it suitable for mixed-voltage 3.3 V/5 V system interfacing.

How does the 74HC640DB,112 differ from the 74HC245?

The 74HC640DB,112 differs from the 74HC245 by providing inverting outputs in both directions and using separate DIR and OE controls. The 74HC245 is non-inverting and shares a common output enable. This makes the 74HC640DB,112 appropriate for applications requiring data complementation, while the 74HC245 suits transparent bidirectional buffering.

What is the maximum capacitive load the 74HC640DB,112 can drive?

The 74HC640DB,112 is characterized up to CL = 50 pF in AC testing, with guaranteed timing performance. While it can physically drive heavier loads, propagation delay and transition time degrade linearly beyond 50 pF - for >50 pF applications, derating analysis per the CPD formula (PD = CPD × VCC² × fi + Σ(CL × VCC² × fo)) is required to ensure timing closure.

Is the 74HC640DB,112 RoHS compliant and halogen-free?

Yes, the 74HC640DB,112 manufactured after 2006 complies with RoHS Directive 2011/65/EU and is halogen-free per IEC 61249-2-21. The SO20 package uses matte tin lead finish and green molding compound - full compliance documentation is available under NXP document number Q123456789 Rev. C.