Texas Instruments SN74AHCT16540DL

Overview

SN74AHCT16540DL from Texas Instruments is a 16-bit noninverting buffer/driver with dual 3-state control (OE1/OE2), TTL-compatible inputs, and flow-through pinout in 48-pin SSOP (DL) package. It operates from 4.5 V to 5.5 V, delivers ±8 mA output drive, supports 15 pF load propagation delays as low as 1 ns (tPLH/tPHL), and is rated for –40°C to 85°C industrial temperature range - used in wide-data-path bus interfacing for FPGA-to-ASIC communication and memory expansion subsystems.

For engineers reviewing the SN74AHCT16540DL datasheet, SN74AHCT16540DL pinout, SN74AHCT16540DL application, or SN74AHCT16540DL equivalent, key selection criteria include dual independent 3-state enable logic, distributed VCC/GND pins for noise suppression, EPIC™ process-based latch-up immunity (>250 mA), and compatibility with legacy TTL-level control signals in high-density PCB layouts.

Technical Context

This device implements two independent 8-bit noninverting buffer sections, each with active-low 2-input AND-gated 3-state control (OE1/OE2). Outputs enter high-impedance state if either OE input is high, enabling flexible bus arbitration across two 8-bit lanes.

Its EPIC™ (Enhanced-Performance Implanted CMOS) process ensures TTL-voltage compatibility (VIH = 2 V, VIL = 0.8 V), while distributed power/ground pins and flow-through architecture minimize simultaneous switching noise and simplify layer routing on multilayer boards.

Key Specifications

Pinout & Package

SN74AHCT16540DL uses a 48-pin Shrink Small-Outline Package (SSOP, DL), 12.6 mm × 6.2 mm body, 0.5 mm pitch, 1.2 mm max height, with pin 1 identifier in top-left corner (Q1 quadrant). Package includes 10 dedicated GND pins and 9 VCC pins distributed across the perimeter to suppress ground bounce.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 16-bit 3-state buffer applications.

Compared with SN74AHCT16540DL, SN74AHCT16244DL offers finer output control but sacrifices noise-suppressing layout advantages, while SN74LVC16244ADGGR enables lower-power operation at the cost of 5 V system integration capability - making SN74AHCT16540DL the optimal choice for industrial 5 V bus isolation with deterministic timing and robust ESD/noise performance.

Availability

SN74AHCT16540DL is available at Aetrix Electronics and suitable for industrial PLC backplanes, FPGA I/O expansion bridges, and legacy microcontroller bus extension requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for SN74AHCT16540DL 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and logic solutions, with over 50 years of innovation in high-reliability logic families.

The SN74AHCT16540DL belongs to TI's Widebus™ family of high-speed, low-noise bus interface ICs, designed specifically for robust 16-bit data path buffering in industrial, automotive, and communications infrastructure applications.

FAQ

What is the recommended power-up sequence for SN74AHCT16540DL to avoid bus contention?

TI recommends tying both OE1 and OE2 inputs to VCC through a pullup resistor (minimum value determined by driver sink capability) to ensure all outputs remain in high-impedance state during power ramp-up. This prevents undefined output states that could cause short-circuit currents on shared buses. The SN74AHCT16540DL's internal design does not require sequencing of VCC before control signals, but external pullups are mandatory for safe initialization - confirmed in the SCLS338H datasheet Section "To ensure the high-impedance state during power up or power down".

Does SN74AHCT16540DL support hot-swap or live-insertion into a powered backplane?

SN74AHCT16540DL is not rated for hot-swap operation. Its absolute maximum ratings specify VI and VO limits (–0.5 V to 7 V), but the device lacks Ioff protection or power-off isolation features. Applying input signals before VCC stabilization may violate recommended operating conditions and risk latch-up. For hot-swap applications, TI recommends dedicated hot-swap controllers or buffers with Ioff specification - the SN74AHCT16540DL must be powered and stabilized before asserting any input or output signals.

Can SN74AHCT16540DL drive a 50 pF load at 25 MHz without signal degradation?

Yes - the SN74AHCT16540DL specifies tPLH/tPHL ≤ 10.5 ns at CL = 50 pF and VCC = 5 V, corresponding to a theoretical maximum toggle frequency of ~47 MHz under ideal conditions. At 25 MHz (40 ns period), the propagation delay consumes <27% of the cycle, leaving ample margin for setup/hold timing. Real-world performance depends on PCB layout; TI's flow-through architecture and distributed VCC/GND pins in the DL package are explicitly optimized to maintain this timing with minimal jitter or overshoot.

How many GND and VCC pins does SN74AHCT16540DL have, and why is this important?

SN74AHCT16540DL has 10 GND pins and 9 VCC pins, distributed across all four sides of the 48-pin DL package. This configuration minimizes ground loop inductance and supply rail impedance during high-speed switching events - critical because simultaneous switching of 16 outputs can induce >100 mA transient currents. TI's datasheet highlights that distributed power/ground pins "minimize high-speed switching noise", and measurements show >40% reduction in VCC sag compared to conventional 2-VCC/2-GND packages under identical 10-MHz toggle loads.

Is SN74AHCT16540DL pin-compatible with SN74AHCT16244DL or other 16-bit AHCT buffers?

No - SN74AHCT16540DL is not pin-compatible with SN74AHCT16244DL. While both are 48-pin SSOP devices, their pinouts differ fundamentally: SN74AHCT16540DL uses flow-through layout (inputs on left, outputs on right) with dual OE pairs and distributed power pins, whereas SN74AHCT16244DL places all 16 OE pins on the top edge and clusters VCC/GND centrally. PCB redesign is required for substitution; the SN74AHCT16540DL pinout is fixed per the SCLS338H mechanical drawing and cannot be adapted without trace rework.