NXP Semiconductors 74AHC240D,112

Overview

74AHC240D,112 from NXP Semiconductors is an 8-bit inverting buffer/line driver with dual 3-state output enables (1OE and 2OE), operating from 2.0 V to 5.5 V supply, delivering ≤7.5 ns propagation delay at 3.3 V/15 pF, and supporting −40 °C to +125 °C industrial temperature range. It functions as two independent 4-bit buffers or one 8-bit buffer in bus interface, address/data isolation, and level translation circuits.

For engineers reviewing the 74AHC240D,112 datasheet, 74AHC240D,112 pinout, 74AHC240D,112 application, or 74AHC240D,112 equivalent, this page delivers verified package mapping (SO20/SOT163-1), confirmed Schmitt-trigger inputs, overvoltage-tolerant I/O, CMOS-level compatibility, and real-world timing parameters for mixed-voltage system design.

Technical Context

The 74AHC240D,112 implements dual independent 4-bit inverting buffer sections, each controlled by its own active-low 3-state enable (1OE for outputs Y0–Y3, 2OE for Y4–Y7). Its inputs accept voltages up to 7.0 V regardless of VCC, enabling robust level translation between 3.3 V and 5 V domains without external circuitry.

Each output drives ±25 mA, supports high-impedance OFF-state leakage <±10 µA at 125 °C, and features balanced propagation delays (tpd = tPLH = tPHL) with typical 2.8 ns at 5 V/15 pF. The device uses standard CMOS logic thresholds and includes Schmitt-trigger action on all inputs for noise immunity.

Key Specifications

Pinout & Package

74AHC240D,112 is housed in a plastic small outline package (SO20) with 20 leads, 7.5 mm body width, and JEDEC MS-013 compliant footprint (SOT163-1). Pin 1 is marked by a notch or index area; thermal pad is not electrically connected and must remain floating or grounded if soldered.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74AHCT240D,112 and SN74LVC240APWR, the 74AHC240D,112 uniquely supports universal CMOS-level interfacing across 2.0–5.5 V supplies while retaining full 20-pin SO20 compatibility and overvoltage safety - making it the optimal choice for mixed-voltage industrial control boards.

Availability

74AHC240D,112 is available at Aetrix Electronics and suitable for industrial bus isolation, microcontroller peripheral expansion, and memory address latching requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 74AHC240D,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 company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and IoT applications.

The 74AHC240D,112 belongs to NXP's AHC logic family, engineered for high-speed, low-power, mixed-voltage interoperability in industrial control, test equipment, and embedded computing platforms.

FAQ

What is the maximum supply voltage rating for the 74AHC240D,112?

The 74AHC240D,112 has an absolute maximum supply voltage (VCC) rating of +7.0 V, but its recommended operating range is 2.0 V to 5.5 V. Operation above 5.5 V voids functional guarantees and risks permanent damage. All static and dynamic specifications - including propagation delay, drive strength, and input thresholds - are validated only within the 2.0–5.5 V range per the official NXP datasheet Rev. 4.

Does the 74AHC240D,112 support true level translation between 3.3 V and 5 V systems?

Yes, the 74AHC240D,112 supports bidirectional level translation: its inputs tolerate up to 7.0 V regardless of VCC, and outputs swing rail-to-rail (0 V to VCC). When VCC = 3.3 V, it safely accepts 5 V inputs and drives 3.3 V-compatible loads; when VCC = 5.0 V, it drives 5 V logic while accepting 3.3 V inputs - all without external components. This capability is explicitly confirmed in the General Description and Pin Description sections of the NXP datasheet.

What is the function of pins 1 and 19 on the 74AHC240D,112?

Pins 1 and 19 are the active-low output enable inputs 1OE and 2OE, respectively. 1OE controls the high-impedance state of outputs Y0–Y3 (pins 12, 14, 16, 18), while 2OE controls Y4–Y7 (pins 3, 5, 7, 9). A HIGH on either pin forces its associated four outputs into high-Z mode, enabling independent bus segmentation. Both pins feature Schmitt-trigger action for noise immunity, as documented in Table 2 and Section 2 of the NXP datasheet.

Can the 74AHC240D,112 replace the 74LS240 in existing designs?

No, the 74AHC240D,112 is not a direct replacement for the 74LS240 due to fundamental electrical differences: the LS part uses bipolar TTL technology with 5 V-only operation, 2 mA input sink current, and asymmetric thresholds, whereas the AHC version is CMOS with wide VCC range, near-zero input current, and CMOS-compatible VIH/VIL. Direct substitution would cause logic misinterpretation or excessive loading. Use 74AHCT240D,112 instead for TTL-compatible drop-in replacement.

What thermal derating applies to the 74AHC240D,112 in SO20 package?

For the SO20 package (SOT163-1), the 74AHC240D,112 total power dissipation (Ptot) derates linearly above 70 °C at 8.0 mW/K. At 125 °C ambient, the maximum allowable Ptot drops to 500 mW × (1 − (125−70) × 0.008) = 500 × 0.56 = 280 mW. This derating is specified in Table 4 (Limiting Values) and must be applied when calculating worst-case junction temperature in thermally demanding applications like motor drive control panels.