Texas Instruments LMK61A2-312M50SIAT

Overview

LMK61A2-312M50SIAT from Texas Instruments is an ultra-low-jitter, factory-programmed LVDS oscillator delivering a precise 312.5 MHz differential clock output with ±50 ppm total frequency tolerance, 90 fs RMS phase jitter (12 kHz–20 MHz), and robust –70 dBc PSRR across 50 kHz–1 MHz supply ripple. It operates from a single 3.3 V supply in industrial temperature range (–40°C to +85°C) and serves as a high-stability timing reference for FPGA transceivers and 10G/25G Ethernet PHYs.

For engineers reviewing the LMK61A2-312M50SIAT datasheet, LMK61A2-312M50SIAT pinout, LMK61A2-312M50SIAT application, or LMK61A2-312M50SIAT equivalent, key selection criteria include LVDS output compliance at 312.5 MHz, 6-pin QFM package compatibility with standard 7050 XO footprints, jitter performance under real-world supply noise, and OE-controlled output disable functionality.

Technical Context

The LMK61A2-312M50SIAT integrates a high-order PLL with internal voltage regulation to generate a fixed 312.5 MHz LVDS clock from its 3.3 V supply, eliminating external loop filters or VCXO components. Its architecture provides deterministic startup behavior (≤10 ms) and fast output enable/disable (≤50 µs) via the OE pin.

Designed for signal integrity-critical applications, it features matched differential output impedance (125 Ω), tightly controlled common-mode voltage (1.2 V), and <250 ps rise/fall times-enabling direct interface to SerDes receivers without AC coupling or level-shifting circuitry.

Key Specifications

Pinout & Package

LMK61A2-312M50SIAT uses a 6-pin QFM (7.0 mm × 5.0 mm) surface-mount package, pin-compatible with industry-standard 7050 XO footprints and optimized for thermal dissipation via GND pad connection to PCB ground plane.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ultra-low-jitter oscillator applications.

Compared with LMK61E2-312M50SIAT, the LMK61A2-312M50SIAT offers lower power and LVDS compatibility out-of-box; versus Si5338A-D-GM, it delivers superior jitter and zero-configuration simplicity at the cost of programmability.

Availability

LMK61A2-312M50SIAT is available at Aetrix Electronics and suitable for 10G/25G Ethernet PHY timing, FPGA transceiver reference clocking, CPRI radio interface clocking, and high-speed ADC/DAC sampling applications requiring stable component supply across production lifecycles.

Supply support for LMK61A2-312M50SIAT 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 high-performance timing solutions for industrial, automotive, and communications markets.

The LMK61XX family was designed specifically to replace quartz-based oscillators in high-speed digital systems where ultra-low jitter, supply noise immunity, and small-footprint integration are critical-targeting next-generation networking, compute, and wireless infrastructure.

FAQ

Is LMK61A2-312M50SIAT pin-compatible with standard 7050-package crystal oscillators?

Yes-it uses a 6-pin QFM (7.0 mm × 5.0 mm) package with identical footprint and pad layout to industry-standard 7050 XO modules, enabling drop-in replacement without PCB redesign. Pin 1 (OE) replaces the traditional ST pin found on many XOs, allowing active output control instead of static enable.

What is the recommended power supply decoupling for LMK61A2-312M50SIAT?

Texas Instruments specifies a three-tier decoupling network: 10 µF (bulk), 1 µF (mid-frequency), and 0.1 µF (high-frequency), all placed as close as possible to the VDD pin with short, low-inductance traces. Capacitors should be 0201 or 0402 size and grounded directly to the inner ground plane using multiple vias.

Can the output format be changed from LVDS to LVPECL or HCSL?

No-the LMK61A2-312M50SIAT is factory-programmed exclusively for LVDS output. Output format is fixed at manufacturing; only LMK61E2 (LVPECL) and LMK61I2 (HCSL) variants support alternative formats. No field reconfiguration or pin-strapping is supported.

Does LMK61A2-312M50SIAT require external load termination resistors?

No-its LVDS outputs are internally terminated to 125 Ω differential, matching standard 100 Ω PCB trace impedance when used with proper 350 mVpp swing. External termination is unnecessary and would degrade signal integrity; only proper 100 Ω differential routing is required.