Texas Instruments LMK61E08-SIAT

Overview

LMK61E08-SIAT from Texas Instruments is an ultra-low jitter (90-fs RMS typical >100 MHz), programmable, EEPROM-integrated oscillator with fractional-N PLL, 4.6–5.6 GHz VCO, and configurable LVPECL/LVDS/HCSL differential outputs up to 1 GHz. It delivers ±25 ppm total frequency tolerance across –40°C to +85°C and supports glitchless digital frequency margining (±1000 ppm) for DVT and standards compliance testing in high-speed networking infrastructure.

For engineers reviewing the LMK61E08-SIAT datasheet, LMK61E08-SIAT pinout, LMK61E08-SIAT application, or LMK61E08-SIAT equivalent, this device serves as a drop-in replacement for crystal/SAW oscillators in FPGA clocking, telecom line cards, and broadcast video timing where sub-200-fs jitter, I²C reprogrammability, and factory-default EEPROM startup are critical selection criteria.

Technical Context

The LMK61E08-SIAT integrates a 50-MHz crystal, fractional-N PLL with delta-sigma noise shaping, and a 4.6–5.6 GHz VCO. Its PLL architecture supports both integer-N (≤200 fs RMS jitter) and fractional-N (≤300 fs RMS jitter) modes, with PFD frequencies selectable at 12.5 MHz (R=4, doubler off) or 100 MHz (R=1, doubler on) to meet xDSL and broadcast video phase noise requirements.

Output configuration is fully programmable via Fast Mode I²C (up to 1000 kHz) and stored in on-chip EEPROM for self-startup. The device uses isolated LDO-regulated analog/digital supplies to achieve –70 dBc PSRR against 50-mVpp supply ripple at 50 kHz–1 MHz, ensuring robust operation in noisy power environments.

Key Specifications

Pinout & Package

LMK61E08-SIAT is housed in a 7.0 mm × 5.0 mm, 6-pin QFM (SIA) package with exposed thermal pad for enhanced thermal performance in high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with Si544BB04209GMR, LMK61E08-SIAT trades 15 fs of jitter for full integration and ease of use; versus AK210-01-EVAL, it adds programmability, tighter tolerance, and margining-making it optimal for high-reliability, field-upgradable systems.

Availability

LMK61E08-SIAT is available at Aetrix Electronics and suitable for telecom infrastructure, FPGA-based test equipment, and medical imaging systems requiring stable component supply, guaranteed long-term availability, and traceable sourcing.

Supply support for LMK61E08-SIAT 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 and embedded processing technologies, with leadership in precision timing, power management, and signal chain solutions.

The LMK61E08-SIAT belongs to TI's PLLatinum™ programmable oscillator family, designed specifically for high-performance reference clocking in networking, computing, and broadcast systems where ultra-low jitter and field configurability are mandatory.

FAQ

What is the default output frequency and format for LMK61E08-SIAT at power-up?

The LMK61E08-SIAT powers up with a factory-programmed default frequency of 70.656 MHz in LVPECL output format, as stored in its internal EEPROM. This behavior occurs regardless of I²C activity unless registers are explicitly rewritten and saved to EEPROM during initialization.

Can LMK61E08-SIAT generate 156.25 MHz with LVDS output and meet ITU-T G.8262 ePRTC phase jitter requirements?

Yes - the LMK61E08-SIAT achieves ≤180 fs RMS (12 kHz–20 MHz) jitter at 156.25 MHz in LVDS mode under integer-N PLL operation, well within the 200 fs RMS limit specified for ePRTC clocks. Measured phase noise at 10 kHz offset is –143 dBc/Hz, satisfying Tier-1 telecom timing standards.

Does LMK61E08-SIAT require external loop filter components?

No - the LMK61E08-SIAT integrates a passive loop filter within the IC. No external resistors or capacitors are needed for PLL stabilization, reducing bill-of-materials count and eliminating tuning variability across production units.

How is thermal performance managed in the 7 mm × 5 mm QFM package?

The LMK61E08-SIAT's QFM package includes an exposed thermal pad connected to the die substrate. TI specifies RθJB = 36.7 °C/W (JEDEC 4-layer board, 3×0.3-mm vias to GND), enabling junction temperatures ≤115°C at 208 mA supply current - verified across –40°C to +85°C ambient with proper PCB copper pour.