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Texas Instruments LMK61A2-312M50SIAR
- Part No.:
- LMK61A2-312M50SIAR
- Manufacturer:
- Texas Instruments
- Category:
- Oscillators
- Package:
- 6-SMD Module
- Datasheet:
-
LMK61A2-312M50SIAR.pdf
- Description:
- SILICONE OSC XO 312.5000MHZ LVDS
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LMK61A2-312M50SIAR from Texas Instruments is an ultra-low jitter LVDS oscillator generating a precise 312.5 MHz reference clock in a 7 mm × 5 mm 6-pin QFM package. It delivers ±50 ppm total frequency stability, 90 fs RMS jitter (typical at >100 MHz), and –70 dBc PSRR across 50 kHz–1 MHz supply ripple - enabling high-speed SerDes timing in 10G/25G Ethernet line cards and FPGA-based baseband units.
For engineers reviewing the LMK61A2-312M50SIAR datasheet, LMK61A2-312M50SIAR pinout, LMK61A2-312M50SIAR application, or LMK61A2-312M50SIAR equivalent, key selection criteria include differential LVDS output compliance (300–480 mV swing, 125 Ω impedance), OE-controlled high-impedance disable, industrial temperature operation (–40°C to +85°C), and compatibility with standard 7050 XO footprints.
Technical Context
The LMK61A2-312M50SIAR integrates a high-performance PLL-based oscillator core with factory-programmed 312.5 MHz LVDS output, eliminating external crystal and loop filter components. Its internal power conditioning provides robust immunity to supply noise, reducing system-level decoupling complexity.
It operates from a single 3.3 V ±5% supply and supports output enable/disable via LVCMOS-compatible OE pin with internal pull-up. The device is pre-configured for LVDS mode only - not reprogrammable in-system - and targets applications requiring deterministic low-jitter clocking without configuration overhead.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Frequency | 312.5 MHz - precisely matches IEEE 802.3ba 25GBASE-KR/CR and CPRI Option 7/8 reference requirements. |
| Output Format | LVDS - differential signaling with 125 Ω output impedance, compatible with TI's TSW14J56, Xilinx Kintex Ultrascale+, and Intel Stratix 10 SerDes receivers. |
| RMS Phase Jitter (12 kHz–20 MHz) | 100–200 fs typical - meets OC-192 SONET and 25G Ethernet jitter budgets without additional cleanup. |
| Total Frequency Tolerance | ±50 ppm - includes initial tolerance, temperature drift (–40°C to +85°C), voltage variation, solder reflow shift, and 10-year aging. |
| Supply Voltage | 3.3 V ±5% - aligns with standard FPGA I/O bank and ASIC core supply rails; eliminates need for dedicated LDO. |
| PSRR | –70 dBc at 50 kHz–1 MHz - suppresses switching noise from adjacent DC/DC converters without ferrite beads or extra filtering. |
| Package | 6-pin QFM (7.0 mm × 5.0 mm) - pin-compatible with industry-standard 7050 XO footprint, enabling drop-in replacement of legacy oscillators. |
Pinout & Package
LMK61A2-312M50SIAR uses a 6-pin QFM (SIA) package measuring 7.0 mm × 5.0 mm × 0.9 mm, with exposed thermal pad connected to GND for enhanced thermal dissipation. Pin 1 (OE) is LVCMOS-compatible with internal pull-up; pins 4 and 5 form the LVDS differential pair (OUTP/OUTN); pin 3 is GND; pin 6 is VDD; pin 2 is NC.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (OE) | Digital control input | Active-low output enable with internal pull-up; drives outputs to high-impedance when low - enables dynamic clock gating in power-sensitive systems. |
| 2 (NC) | No-connect | Unbonded die pad; must remain unconnected on PCB to avoid parasitic coupling or ESD path disruption. |
| 3 (GND) | Analog/digital ground | Common return for all internal circuitry; requires direct connection to solid ground plane via ≥3 thermal vias (0.3 mm diameter). |
| 4 (OUTN) | Differential LVDS output | Inverted leg of 312.5 MHz LVDS signal; routed as matched-length, controlled-impedance pair (100 Ω differential) to receiver. |
| 5 (OUTP) | Differential LVDS output | Non-inverted leg of 312.5 MHz LVDS signal; maintains <10 ps skew vs. OUTN for optimal common-mode rejection. |
| 6 (VDD) | Power supply | 3.3 V analog supply; requires local 10 µF/1 µF/0.1 µF bypass network mounted on component side with shortest possible trace to pin. |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-low jitter (90 fs RMS typical) | Enables clean sampling in 25G+ SerDes PHYs without external jitter cleaners, reducing BOM count and board area. |
| –70 dBc PSRR at 50 kHz–1 MHz | Allows shared 3.3 V rail with noisy digital ICs (e.g., FPGAs, processors), eliminating dedicated low-noise LDOs. |
| ±50 ppm total frequency stability | Meets telecom-grade timing accuracy over full industrial temperature range and 10-year lifetime - no recalibration needed. |
| LVDS output (300–480 mV swing, 125 Ω) | Direct interface to Xilinx UltraScale+ GTY transceivers and Intel Stratix 10 H-tile without external termination resistors. |
| 6-pin 7050-compatible QFM package | Enables mechanical and layout compatibility with existing XO footprints, minimizing PCB redesign effort during upgrade. |
Applications
| 10G/25G Ethernet Line Cards | FPGA-Based Baseband Units (BBUs) |
|---|---|
|
Use Scenario: Providing reference clocks to multiple 25G KR/KR4 SerDes lanes in carrier-grade switch/router line cards. IC Role / Device Role / Timing Role: Primary low-jitter system clock source for PHY layer synchronization and gearbox logic. Use Value: 100–200 fs RMS jitter ensures BER <1e–12 under worst-case channel loss, eliminating need for retiming ICs. |
Use Scenario: Clocking multi-core FPGA fabric and high-speed ADC/DAC interfaces in 5G wireless infrastructure BBUs. IC Role / Device Role / Timing Role: Central timing hub delivering synchronized 312.5 MHz and derived clocks to processing blocks. Use Value: ±50 ppm stability maintains CPRI/ECPRI frame alignment across temperature and aging, avoiding packet slips. |
| Test & Measurement Equipment | Medical Imaging Systems |
|
Use Scenario: Generating stable sampling clocks for high-resolution oscilloscopes and bit-error-rate testers operating above 20 GS/s. IC Role / Device Role / Timing Role: Low-phase-noise clock generator for ADC front-end sampling and digital signal processing clocks. Use Value: –162 dBc/Hz phase noise floor at 10 MHz offset preserves SNR in wideband RF digitization paths. |
Use Scenario: Synchronizing time-of-flight measurements and parallel data acquisition in PET/MRI scanner backends. IC Role / Device Role / Timing Role: Deterministic jitter-free timing reference for high-speed data capture and beamforming engines. Use Value: Industrial temperature rating (–40°C to +85°C) and 125°C junction limit ensure reliability in thermally constrained enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar ultra-low jitter oscillator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LMK61E2-312M50SIAR | Same 312.5 MHz output but LVPECL format (1 GHz max), higher current draw (208 mA vs. 196 mA), ±50 ppm tolerance. | Requires 50 Ω AC-coupled termination and negative voltage margin; unsuitable for LVDS-only receivers. | Select only if system uses LVPECL inputs (e.g., older ASICs) and can accommodate higher power and different termination. |
| Si5338A-B-GM | Programmable 4-output clock generator (I²C-configurable), 100 fs RMS jitter, ±10 ppm initial accuracy, 3.3 V supply. | Supports multiple frequencies and formats simultaneously; requires firmware initialization and external EEPROM. | Choose when flexible multi-frequency generation is needed; avoid if single-fixed-frequency simplicity and zero-configuration are priorities. |
Compared with LMK61E2-312M50SIAR and Si5338A-B-GM, the LMK61A2-312M50SIAR offers plug-and-play LVDS timing with lowest design overhead, while maintaining best-in-class jitter and industrial reliability - ideal for volume production where configuration complexity and supply chain variability must be minimized.
Availability
LMK61A2-312M50SIAR is available at Aetrix Electronics and suitable for 10G/25G Ethernet line cards, FPGA-based baseband units, test and measurement equipment, and medical imaging systems requiring stable component supply, long-term lifecycle support, and guaranteed traceability.
Supply support for LMK61A2-312M50SIAR 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 headquartered in Dallas, Texas, specializing in analog, embedded processing, and high-performance timing solutions for industrial, automotive, and communications markets.
The LMK61XX family was designed to replace quartz-based oscillators in high-speed digital systems, delivering ultra-low jitter, superior PSRR, and factory-programmed flexibility - with the LMK61A2 series optimized specifically for LVDS output in telecom and datacenter infrastructure.
FAQ
What output format does the LMK61A2-312M50SIAR support?
The LMK61A2-312M50SIAR is factory-programmed exclusively for LVDS output. It delivers a 312.5 MHz differential signal with 300–480 mV swing, 125 Ω output impedance, and 45–55% duty cycle. Unlike programmable variants, it does not support LVPECL or HCSL modes - the LMK61A2-312M50SIAR is fixed-function and requires no configuration.
Does the LMK61A2-312M50SIAR require external configuration or programming?
No, the LMK61A2-312M50SIAR is fully factory-programmed and operates immediately upon power-up with no external configuration required. It has no I²C, SPI, or pin-strapping interface. The LMK61A2-312M50SIAR is a turnkey oscillator - simply apply 3.3 V, connect OE high (or leave floating due to internal pull-up), and use the LVDS outputs.
What is the maximum allowable supply voltage ripple for the LMK61A2-312M50SIAR?
The LMK61A2-312M50SIAR maintains –70 dBc PSRR against 50 mVpp sinusoidal ripple from 50 kHz to 1 MHz. This means a 50 mVpp ripple on the 3.3 V rail induces only –70 dBc spurious content in the 312.5 MHz output spectrum. The LMK61A2-312M50SIAR thus tolerates typical DC/DC switching noise without external filtering beyond standard 10 µF/1 µF/0.1 µF bypassing.
Can the LMK61A2-312M50SIAR be used in place of a 7050-package crystal oscillator?
Yes, the LMK61A2-312M50SIAR uses a 7 mm × 5 mm 6-pin QFM package that is mechanically and pinout-compatible with industry-standard 7050 XO footprints. Pin 1 (OE) maps to the enable function (often unused in basic XOs), while pins 4/5 (OUTP/OUTN) replace the single-ended output. The LMK61A2-312M50SIAR drops into existing layouts with minimal routing changes.
What is the startup time and output enable delay for the LMK61A2-312M50SIAR?
The LMK61A2-312M50SIAR has a typical start-up time of 10 ms - defined as the interval from VDD reaching 3.135 V to valid output - and an output enable delay of 50 µs from OE rising to VIH (1.4 V). These values are specified over –40°C to +85°C and ensure deterministic timing behavior in power-sequenced systems using the LMK61A2-312M50SIAR.
LMK61A2-312M50SIAR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- LMK61XX
- Package/Case:
- 6-SMD Module
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Base Resonator:
- Silicon
- Type:
- XO (Standard)
- Frequency:
- 312.5 MHz
- Function:
- Enable/Disable
- Output:
- LVDS
- Voltage - Supply:
- 3.3V
- Frequency Stability:
- ±50ppm
- Absolute Pull Range (APR):
- -
- Operating Temperature:
- -40°C ~ 85°C
- Spread Spectrum Bandwidth:
- -
- Current - Supply (Max):
- 196mA
- Ratings:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 6-QFM (7x5)
- Size / Dimension:
- 0.276" L x 0.197" W (7.00mm x 5.00mm)
- Height - Seated (Max):
- 0.045" (1.15mm)
LMK61A2-312M50SIAR FAQ
1.How can I place an order for LMK61A2-312M50SIAR through Aetrix?
Please submit a Request for Quotation (RFQ) for LMK61A2-312M50SIAR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LMK61A2-312M50SIAR reliable?
The price and inventory of LMK61A2-312M50SIAR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LMK61A2-312M50SIAR is usually 5 days.
3.What payment methods are accepted for LMK61A2-312M50SIAR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LMK61A2-312M50SIAR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LMK61A2-312M50SIAR?
LMK61A2-312M50SIAR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LMK61A2-312M50SIAR order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LMK61A2-312M50SIAR?
For technical support, including LMK61A2-312M50SIAR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LMK61A2-312M50SIAR requirements.
6.How does Aetrix verify that LMK61A2-312M50SIAR is sourced from the original manufacturer or authorized distributors?
All LMK61A2-312M50SIAR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LMK61A2-312M50SIAR meets industry standards.
7.What is the process for return or replacement of LMK61A2-312M50SIAR?
All LMK61A2-312M50SIAR units undergo pre-shipment inspection (PSI). If there is an issue with LMK61A2-312M50SIAR, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LMK61A2-312M50SIAR part is unused and in its original packaging.
Return procedure for LMK61A2-312M50SIAR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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