Texas Instruments SN74LVC1404DCUR

Overview

SN74LVC1404 from Texas Instruments is a crystal oscillator driver IC containing one Schmitt-trigger inverter (A→Y), two unbuffered inverters (XIN→XOUT, XIN→OSCOUT), and an oscillator control input (CTRL). It operates from 1.65 V to 5.5 V, supports 15 kHz–28 MHz crystal/resonator frequencies, delivers ±24 mA output drive at 3.3 V, and draws ≤10 µA in standby when CTRL is low. It is used in clock generation for servers, network switches, and wearable health devices.

For engineers reviewing the SN74LVC1404 datasheet, SN74LVC1404 pinout, SN74LVC1404 application, or SN74LVC1404 equivalent, this page provides verified functional architecture, validated pin functions for the DCUR (VSSOP-8) package, confirmed oscillator enable/disable behavior, real-world timing specs at multiple VCC levels, and two documented alternative oscillator drivers with explicit functional and interface differences.

Technical Context

The SN74LVC1404 implements a three-inverter Pierce oscillator core: XIN and XOUT form the gain stage across a crystal or ceramic resonator; OSCOUT provides a direct unbuffered output of the same stage; and CTRL disables the oscillator by forcing XOUT low. The Schmitt-trigger inverter (A→Y) operates independently as a signal conditioner with hysteresis (ΔVT = 0.37–1.11 V depending on VCC).

It uses Ioff circuitry to isolate inputs/outputs during partial power-down, supports live insertion, and tolerates input voltages up to 5.5 V regardless of VCC level. Its open-loop gain enables stable oscillation across 15 kHz–28 MHz without external active components, with propagation delays ranging from 0.9 ns (A→Y, VCC = 5 V, CL = 15 pF) to 28.2 ns (CTRL→XOUT, same conditions).

Key Specifications

Pinout & Package

VSSOP-8 (DCUR) package: 2.30 mm × 2.00 mm body, 0.5 mm pitch, exposed pad optional, RoHS-compliant NiPdAu lead finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar oscillator driver applications.

Compared with SN74LVC1404, SN74LVC1G14DBVR lacks oscillator functionality entirely and cannot replace it in crystal-based designs, while CDCE62005RGZT offers far greater flexibility but introduces complexity, cost, and power overhead unsuitable for simple fixed-frequency clock generation.

Availability

SN74LVC1404DCUR is available at Aetrix Electronics and suitable for server clock distribution, wearable health device timing, network switch synchronization, PC/notebook reference clocking, and electronic point-of-sale systems requiring stable component supply and long-term production continuity.

Supply support for SN74LVC1404DCUR 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 company specializing in analog, embedded processing, and connectivity technologies, with over 50 years of leadership in precision timing and logic solutions.

The SN74LVC1404 belongs to TI's LVC low-voltage CMOS logic family, designed specifically for reliable, low-power oscillator implementation in space-constrained, mixed-voltage digital systems.

FAQ

What is the primary function of the CTRL pin on the SN74LVC1404DCUR?

The CTRL pin on the SN74LVC1404DCUR is an active-high oscillator enable input. When driven low, it disables the internal oscillator circuit and forces the XOUT output to a logic low state, reducing ICC to ≤10 µA. This enables dynamic clock gating in power-sensitive applications. To ensure reliable disable during power-up, TI recommends connecting CTRL to GND via a pulldown resistor.

Can the SN74LVC1404DCUR drive a 25 MHz crystal without external components?

Yes - the SN74LVC1404DCUR is explicitly validated for 25 MHz crystal operation in TI's datasheet (SCES469F). It requires only external load capacitors (C1 ≈ C2 ≈ 30 pF) and a feedback resistor (RF ≈ 2.2 MΩ) to bias the XIN/XOUT inverter in its linear region. No additional active components are needed, making it a complete, minimal-footprint oscillator solution.

How does the Schmitt-trigger inverter (A→Y) differ from the unbuffered inverters in the SN74LVC1404DCUR?

The Schmitt-trigger inverter (pins A and Y) provides hysteresis (ΔVT = 0.37–1.11 V) for noise immunity and clean edge regeneration, while the unbuffered inverters (XIN→XOUT and XIN→OSCOUT) deliver high open-loop gain for crystal oscillation. The Y output is buffered and rail-to-rail; XOUT and OSCOUT are unbuffered and optimized for low-capacitance crystal interface - they are not intended for direct fanout to multiple loads.

Is the SN74LVC1404DCUR compatible with 1.8 V supply voltage?

Yes - the SN74LVC1404DCUR is fully specified for 1.65 V to 5.5 V VCC operation. At 1.8 V, it supports 15 kHz–28 MHz oscillation, delivers ≥4 mA output drive (IOL/IOH), and maintains propagation delay ≤15.1 ns (A→Y, CL = 15 pF). All electrical characteristics, including VT+ and VT− thresholds, are guaranteed across this full range.

What package type does the SN74LVC1404DCUR use, and what are its key mechanical features?

The SN74LVC1404DCUR uses the VSSOP-8 (DCU) package: 2.30 mm × 2.00 mm body size, 0.5 mm lead pitch, 8-pin surface-mount format with gull-wing leads. It carries RoHS-compliant NiPdAu lead finish, meets MSL Level-1 (unlimited floor life), and operates from –40°C to +125°C. Its compact footprint supports high-density layouts in portable and networking equipment.