Texas Instruments LMK61E2-SIAR

Overview

LMK61E2-SIAR from Texas Instruments is an ultra-low jitter (90 fs RMS typical >100 MHz), programmable oscillator with integrated fractional-N PLL, VCO (4.6–5.6 GHz), and on-chip EEPROM. It delivers user-configurable LVPECL (up to 1 GHz), LVDS (up to 900 MHz), or HCSL (up to 400 MHz) outputs at 3.3 V, with ±50 ppm total frequency tolerance and industrial temperature range (–40°C to +85°C). It serves as a high-stability clock source for FPGA/processor reference, network line cards, and test equipment.

For engineers reviewing the LMK61E2-SIAR datasheet, LMK61E2-SIAR pinout, LMK61E2-SIAR application, or LMK61E2-SIAR equivalent, this page provides verified technical context, real-world timing performance data, I²C programmability details, PSRR robustness metrics, and validated alternative options for system-level clock design and supply chain continuity.

Technical Context

The LMK61E2-SIAR implements a fractional-N PLL architecture with integrated VCO (4.6–5.6 GHz), supporting both integer and fractional synthesis modes. Its phase noise floor reaches –165 dBc/Hz (LVPECL @156.25 MHz, 10 MHz offset), and it achieves <200 fs RMS jitter (12 kHz–20 MHz) in integer mode and <300 fs RMS in fractional mode.

It features self-starting operation via factory-programmed EEPROM (default: 156.25 MHz LVPECL), full in-system reconfiguration via I²C interface (100–400 kHz), and dual-stage frequency margining (coarse via output divider, fine via oscillator tuning). Internal LDOs provide –70 dBc PSRR across 50 kHz–1 MHz supply ripple.

Key Specifications

Pinout & Package

LMK61E2-SIAR uses a 7 mm × 5 mm, 8-pin QFM (SIA) package with exposed thermal pad. Pin functions are validated per TI SNAS674C Rev. May 2025.

Key Features

Applications

Equivalent & Alternatives

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

Compared with Si5338A-D-GM, LMK61E2-SIAR offers superior jitter (90 vs. 115 fs) and smaller footprint (7×5 mm vs. 4×4 mm), while the LMK61E0M-SIAR trades EEPROM autonomy for host-dependent configuration-making LMK61E2-SIAR optimal for standalone, fail-safe clocking in resource-constrained systems.

Availability

LMK61E2-SIAR is available at Aetrix Electronics and suitable for network infrastructure, FPGA reference designs, test equipment, and medical imaging systems requiring stable component supply and guaranteed long-term manufacturability.

Supply support for LMK61E2-SIAR 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 clock solutions, with decades of expertise in precision timing and signal integrity.

The LMK61E2 product line targets high-performance clock generation for datacenter, telecom, and instrumentation applications-designed to replace legacy crystal oscillators with programmable, low-jitter alternatives that simplify system design and improve timing margin.

FAQ

What is the default output configuration of the LMK61E2-SIAR at power-up?

The LMK61E2-SIAR powers up with factory-programmed EEPROM settings: 156.25 MHz LVPECL output, OE enabled, and I²C address set to 0x56 (ADD = open). No host intervention is required for immediate clock generation, making it ideal for plug-and-play deployment in unmanaged systems.

Can the LMK61E2-SIAR generate non-standard frequencies like 161.1328125 MHz?

Yes-the LMK61E2-SIAR supports arbitrary frequencies via its fractional-N PLL. The 161.1328125 MHz output is explicitly characterized in the datasheet (SNAS674C), with verified phase noise (–161 dBc/Hz @10 MHz offset, LVPECL) and jitter (<300 fs RMS), confirming full functionality for proprietary SerDes protocols and custom sampling rates.

How does the LMK61E2-SIAR handle power supply noise compared to standard XO devices?

Unlike basic crystal oscillators, the LMK61E2-SIAR integrates on-die LDOs and achieves –70 dBc PSRR from 50 kHz to 1 MHz-rejecting switching regulator noise that would otherwise modulate the VCO and increase jitter. This eliminates the need for ultra-low-noise LDOs or extensive LC filtering in cost-sensitive power delivery networks.

Is the SIA (QFM) package RoHS-compliant and lead-free?

Yes-the LMK61E2-SIAR SIA package is RoHS-compliant and lead-free, meeting JEDEC J-STD-020 MSL3 moisture sensitivity requirements. It supports standard Pb-free reflow profiles (peak 260°C), and TI's official packaging documentation confirms halogen-free construction and full compliance with EU Directive 2011/65/EU.