Texas Instruments SN74LVC540ANSR

Overview

SN74LVC540ANSR from Texas Instruments is an octal inverting buffer/driver with 3-state outputs, designed for bus interface and signal redriving in 1.65V–3.6V systems. It features dual active-low output enables (OE1/OE2), 5.3ns max propagation delay at 3.3V, 5.5V-tolerant inputs, and Ioff support for live insertion - used in transmission line driving and controller reset hold applications.

For engineers reviewing the SN74LVC540ANSR datasheet, SN74LVC540ANSR pinout, SN74LVC540ANSR application, or SN74LVC540ANSR equivalent, key selection criteria include 3-state control logic, mixed-mode voltage compatibility (5V inputs into 3.3V VCC), ground bounce <0.8V, VOH undershoot >2V, and thermal performance in TSSOP-20 packaging.

Technical Context

The SN74LVC540ANSR implements eight independent inverting buffers sharing two synchronized active-low output enable inputs (OE1 and OE2), requiring both to be low for output activation. Its CMOS input structure accepts up to 5.5V regardless of VCC, enabling mixed-voltage interfacing between 5V peripherals and 3.3V logic domains.

It employs balanced CMOS 3-state outputs capable of sourcing/sinking ±24mA at 3V, with Ioff circuitry ensuring near-zero leakage (<10μA) during partial power-down. The device meets JESD78 latch-up immunity (>100mA) and supports high-speed signal integrity via controlled edge rates and low output capacitance (5.5pF).

Key Specifications

Pinout & Package

SN74LVC540ANSR is supplied in a 20-pin TSSOP (PW) package measuring 6.5mm × 6.4mm (body: 6.5mm × 4.4mm), optimized for high-density routing and thermal dissipation (RθJA = 120.3°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC240ANSR and 74LVC540APW,118, the SN74LVC540ANSR provides guaranteed inverting functionality with best-in-class ground bounce performance (<0.8V), making it preferred for noise-sensitive reset and enable signaling where signal polarity and signal integrity are jointly critical.

Availability

SN74LVC540ANSR is available at Aetrix Electronics and suitable for industrial bus interface, embedded controller reset management, and LED indicator driving requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SN74LVC540ANSR 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 and embedded processing technologies, with decades of experience in logic IC design and manufacturing.

The SN74LVC540ANSR belongs to TI's LVC (Low-Voltage CMOS) logic family, engineered for interoperability across mixed-voltage systems and optimized for low-power, high-noise-immunity digital interfacing in industrial and automotive applications.

FAQ

What is the function of the dual output enable pins (OE1 and OE2) on the SN74LVC540ANSR?

The SN74LVC540ANSR requires both OE1 and OE2 to be logic low simultaneously to enable all eight inverting outputs. If either pin is high, all Y1–Y8 outputs enter high-impedance state. This dual-enable architecture enhances system-level fault tolerance - for example, tying OE1 to a system supervisor and OE2 to a processor GPIO allows coordinated bus isolation during power sequencing or error recovery. The SN74LVC540ANSR datasheet specifies this behavior in its Function Table (Table 7-1).

Can the SN74LVC540ANSR safely interface a 5V microcontroller with a 3.3V FPGA?

Yes - the SN74LVC540ANSR accepts input voltages up to 5.5V while operating from a 3.3V VCC, enabling direct connection from 5V-tolerant MCU GPIOs to 3.3V FPGA inputs without external level shifters. Its CMOS inputs draw only ±5μA leakage, and the device maintains full logic thresholds (VIH/VIL) across the 1.65–3.6V supply range. This mixed-mode capability is explicitly validated in the SN74LVC540ANSR Recommended Operating Conditions table.

What is the maximum capacitive load the SN74LVC540ANSR can drive while meeting timing specifications?

The SN74LVC540ANSR is characterized to drive loads ≤50pF while maintaining its specified 5.3ns max propagation delay at 3.3V. Exceeding this capacitance increases tpd nonlinearly and may cause signal degradation, especially on longer traces. TI's Application Report SLLA169 confirms that layout practices - including short traces, ground planes, and series damping resistors - are essential to preserve timing when approaching this limit. The SN74LVC540ANSR's 5.5pF typical output capacitance contributes minimally to total load.

How does the Ioff feature of the SN74LVC540ANSR support hot-swap applications?

The Ioff feature in the SN74LVC540ANSR disables all outputs and limits leakage current to <10μA when VCC = 0V, preventing back-driving of live backplane rails during card insertion/removal. This eliminates risk of damaging upstream supplies or corrupting data on shared buses. The SN74LVC540ANSR's Ioff specification is tested per JEDEC JESD78 and verified across –40°C to +125°C, making it suitable for telecom and industrial modular systems requiring true hot-plug capability.

Is the SN74LVC540ANSR pin-compatible with older 74-series logic devices?

No - the SN74LVC540ANSR uses a flow-through pinout (A1–A8 on one side, Y1–Y8 on the opposite) distinct from legacy 74LS540 or 74HC540 packages. While functionally equivalent to the SN74LVC240ANSR in pin count and footprint, it is not pin-compatible with non-LVC variants due to differing enable logic (dual OE vs. single OE) and voltage ratings. Always verify mechanical dimensions and signal mapping using the SN74LVC540ANSR Pin Configuration diagram (Figure 4-2) before PCB redesign.