Texas Instruments LMK61E2BAA-SIAR

Overview

LMK61E2BAA-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 factory-configured 156.25 MHz LVDS output in a 7 mm × 5 mm QFM-8 package, operates at 3.3 V, and supports I²C reprogramming for system-level frequency margining and custom clock synthesis in FPGA/processor timing applications.

For engineers reviewing the LMK61E2BAA-SIAR datasheet, LMK61E2BAA-SIAR pinout, LMK61E2BAA-SIAR application, or LMK61E2BAA-SIAR equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, application-specific use cases, and confirmed alternative options - all grounded in TI's production-grade SNAS674C datasheet and package documentation.

Technical Context

The LMK61E2BAA-SIAR integrates a 50 MHz crystal-based oscillator, fractional-N PLL with delta-sigma noise shaping, and a universal differential output buffer configurable as LVDS (up to 900 MHz), LVPECL (up to 1 GHz), or HCSL (up to 400 MHz). Its internal LDO-regulated power conditioning achieves –70 dBc PSRR from 50 kHz to 1 MHz, isolating the PLL from supply noise.

It features self-startup from factory-programmed EEPROM, fine/coarse frequency margining via I²C, and full in-system register reconfiguration. The device uses a 9-bit output divider (5–511) and supports integer/fractional feedback dividers to synthesize precise frequencies across telecom, computing, and test equipment reference domains.

Key Specifications

Pinout & Package

LMK61E2BAA-SIAR uses a 7 mm × 5 mm, 8-pin QFM (SIA) package with exposed thermal pad. Pin 1 is OE (output enable), pin 2 is ADD (I²C address LSB), pins 4 and 5 are differential outputs (OUTP/OUTN), pin 3 is GND, pin 6 is VDD (3.3 V), pin 7 is SDA (open-drain I²C data), and pin 8 is SCL (open-drain I²C clock).

Key Features

Applications

Equivalent & Alternatives

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

Compared with Si510-PROG-A-GM, LMK61E2BAA-SIAR offers faster startup and autonomous operation via EEPROM, while LMK62E2BAA-SIAR delivers measurable jitter reduction and broader frequency coverage without changing board layout or firmware architecture.

Availability

LMK61E2BAA-SIAR is available at Aetrix Electronics and suitable for high-speed networking, FPGA timing, medical imaging, and 5G infrastructure requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LMK61E2BAA-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 high-performance timing devices for mission-critical systems.

The LMK61E2 series belongs to TI's PLLatinum™ programmable oscillator product line, designed specifically for applications demanding ultra-low jitter, flexible output formats, and robust power supply immunity in telecom, computing, and test equipment.

FAQ

What is the default output frequency and format for LMK61E2BAA-SIAR?

The LMK61E2BAA-SIAR is factory-programmed to output 156.25 MHz LVDS upon power-up, using its internal EEPROM. This default configuration requires no I²C initialization and remains active unless overwritten via the I²C interface. The device retains this setting across power cycles due to non-volatile EEPROM storage.

Can LMK61E2BAA-SIAR generate frequencies other than 156.25 MHz?

Yes - the LMK61E2BAA-SIAR uses a fractional-N PLL with a 4.6–5.6 GHz VCO and 9-bit output divider (5–511) to synthesize frequencies from 10 MHz to 900 MHz in LVDS mode. Configuration is done via I²C registers or updated EEPROM settings, enabling custom frequencies like 161.1328125 MHz for specific SerDes protocols.

Does LMK61E2BAA-SIAR require external termination resistors?

Yes - LVDS operation requires a 100 Ω differential termination resistor between OUTP and OUTN, placed as close as possible to the load. The device itself does not integrate termination; its LVDS driver is designed for 125 Ω output impedance, making external 100 Ω matching essential for signal integrity and EMI control.

How does the ADD pin affect I²C communication?

The ADD pin sets the LSB of the I²C slave address: tied to GND = 00, floating = 01, tied to VDD = 10. This allows up to three LMK61E2BAA-SIAR devices on the same I²C bus without address conflict. The full 7-bit address is 11000xx (0x60–0x62), enabling multi-oscillator synchronization in complex timing architectures.