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Analog Devices Inc. SIT3921AI-2CF-33NZ125.000000X
- Part No.:
- SIT3921AI-2CF-33NZ125.000000X
- Manufacturer:
- Analog Devices Inc.
- Category:
- Oscillators
- Package:
- -
- Datasheet:
-
SIT3921AI-2CF-33NZ125.000000X.pdf
- Description:
- SIT3921 - 1 to 220 MHz, Differen
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Product details
Overview
SIT3921AI-2CF-33NZ125.000000X from SiTime Corporation is a digitally controlled differential oscillator (DCXO) with factory-programmed 125.000000 MHz output, ±1600 ppm pull range, LVDS output, 3.3 V supply, and industrial temperature range (–40°C to +85°C). It delivers <0.75 ps RMS phase jitter (12 kHz–20 MHz), 45–55% duty cycle, and supports serial tri-level frequency tuning for telecom and instrumentation timing systems.
For engineers reviewing the SIT3921AI-2CF-33NZ125.000000X datasheet, SIT3921AI-2CF-33NZ125.000000X pinout, SIT3921AI-2CF-33NZ125.000000X application, or SIT3921AI-2CF-33NZ125.000000X equivalent, this page provides verified electrical specs, pin-level interface details, real-world use cases in SONET and satellite systems, and validated alternative options for differential clocking designs requiring high linearity and low jitter.
Technical Context
The SIT3921AI-2CF-33NZ125.000000X implements a MEMS-based digitally controlled oscillator architecture with two configurable frequency control modes: Mode 1 (16-bit resolution, 25 kSPS update rate) and Mode 2 (23-bit resolution, 12.5 kSPS). Its digital programming pin (DP) accepts tri-level return-to-middle signaling for precise frequency adjustment without external DACs or analog components.
It supports both LVDS and LVPECL output configurations-this variant uses LVDS with 200–500 mV differential swing, 1.125–1.375 V common-mode offset, and 360–600 ps rise/fall times. The device achieves ≤1% pull range linearity and retains programmed settings for >1,000 years across –40°C to +125°C storage conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Frequency | 125.000000 MHz - factory-programmed nominal frequency, stable over full operating range |
| Frequency Stability | ±10 ppm - includes initial tolerance, temperature, voltage, and load variation; enables tight system synchronization |
| Pull Range | ±1600 ppm - digitally adjustable via DP pin; supports wide dynamic frequency correction in PLL loops |
| RMS Phase Jitter | 0.5–0.75 ps - measured 12 kHz–20 MHz bandwidth; meets OC-192/SONET and 10G Ethernet jitter budgets |
| Supply Voltage | 3.3 V ±10% - compatible with standard logic rails; supports 2.97–3.63 V operation |
| Operating Temp | –40°C to +85°C - industrial-grade thermal performance; no derating required up to max ambient |
| Output Type | LVDS - differential signaling with 200–500 mV swing; eliminates common-mode noise in high-speed backplanes |
| Current Consumption | 47–55 mA - excludes termination current; enables power-aware clock tree design in dense PCB layouts |
Pinout & Package
Package: 5.0 mm × 3.2 mm × 0.75 mm 6-pin surface-mount ceramic package (SiT3921 "C" variant), RoHS-compliant, MSL1 rated.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (DP) | Digital Programming Input | Tri-level serial interface pin; accepts 0.2×VDD/0.4–0.6×VDD/0.8×VDD logic levels for frequency control register writes |
| 2 (NC) | No Connect | Internally unconnected; must remain floating or grounded per layout guidelines-no routing or vias |
| 3 (GND) | Power Ground | Primary reference for all internal circuitry and output common-mode; requires low-inductance connection to PCB ground plane |
| 4 (OUT+) | Differential Output Positive | LVDS true output; pairs with OUT– to deliver 200–500 mV differential swing into 100 Ω termination |
| 5 (OUT–) | Differential Output Negative | LVDS complementary output; matched delay and amplitude to OUT+ for <1 ps skew in high-speed links |
| 6 (VDD) | Power Supply | 3.3 V input; requires 0.1 µF decoupling capacitor placed within 2 mm of pin per SiTime layout recommendations |
Key Features
| Feature | Design Value |
|---|---|
| Factory-programmable frequency | 125.000000 MHz set at wafer test; eliminates post-solder calibration and reduces BOM count |
| Digital pull range linearity | ≤1% deviation across ±1600 ppm range; enables accurate closed-loop frequency control without lookup tables |
| Low-phase-jitter architecture | 0.5 ps typical RMS phase jitter (12 kHz–20 MHz); supports 10G/25G SerDes compliance without external jitter cleaners |
| Tri-level serial interface | Single-wire DP pin with MSB-first 40-bit frame format; replaces I²C/SPI interfaces and saves GPIO resources |
| Long-term frequency retention | Programmed settings retained >1000 years at –40°C to +125°C; eliminates recalibration in field-deployed equipment |
| Industrial temperature support | Full specification over –40°C to +85°C; operates reliably in base station, test gear, and satellite payload environments |
Applications
| SONET/SDH Timing Recovery | High-Speed Instrumentation Clocking |
|---|---|
Use Scenario: Recovering and regenerating 155.52 MHz or 622.08 MHz clocks in OC-3/OC-12 line cards with adaptive frequency alignment. IC Role / Device Role / Timing Role: Digitally tunable reference oscillator providing jitter-clean, temperature-stable clock for CDR circuits and elastic buffers. Use Value: ±1600 ppm pull range and ≤1% linearity enable precise drift compensation without external DACs or analog loop filters. |
Use Scenario: Synchronizing multi-channel ADC/DAC sampling in automated test equipment (ATE) with sub-picosecond timing precision. IC Role / Device Role / Timing Role: Low-jitter LVDS clock source driving parallel data acquisition paths with deterministic inter-channel skew. Use Value: 0.5 ps RMS phase jitter ensures <0.1 LSB timing error in 16-bit, 1 GSPS converters under full-scale operation. |
| Satellite Communication Modems | Broadband Access Gateways |
Use Scenario: Providing agile local oscillator reference in Ka-band transceivers where Doppler shift compensation requires real-time frequency updates. IC Role / Device Role / Timing Role: DCXO serving as programmable IF clock generator with fast settling (<30 µs) after digital reprogramming. Use Value: Mode 2's 23-bit resolution and 12.5 kSPS update rate allow 1 Hz step size at 125 MHz while maintaining lock in closed-loop tracking loops. |
Use Scenario: Clocking GPON/EPON optical line terminals (OLTs) requiring strict jitter compliance and thermal stability across outdoor cabinet temperatures. IC Role / Device Role / Timing Role: Primary system clock generator delivering 125 MHz to MAC, PHY, and encryption engines with shared domain timing. Use Value: ±10 ppm stability over –40°C to +85°C eliminates need for temperature-compensated crystal oscillators (TCXOs) in cost-sensitive broadband hardware. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar digitally controlled differential oscillator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Si570-B-GM | IC-based PLL synthesizer with I²C interface; 10 MHz–1.4 GHz output; higher power (120 mA), wider frequency coverage but no factory-programmed fixed frequency. | Used where flexible frequency synthesis is needed instead of fixed-frequency tuning; less suitable for jitter-critical SONET recovery. | Select when variable output frequency generation is required; avoid if fixed 125 MHz with minimal jitter is mandatory. |
| MAX2679EUT+T | VCO-based DCXO with analog tuning voltage input; ±500 ppm range; 2.7–5.5 V supply; no digital interface or guaranteed linearity spec. | Deployed in legacy RF front-ends where analog voltage control is already present; lacks digital programmability and long-term retention. | Choose only for analog-centric designs; not recommended for new digital-control architectures requiring traceable, repeatable tuning. |
Compared with SIT3921AI-2CF-33NZ125.000000X, the Si570 offers broader frequency agility but higher jitter and power, while the MAX2679 relies on analog tuning with no digital repeatability-making the SIT3921 the optimal choice for deterministic, low-jitter, digitally reconfigurable 125 MHz timing in telecom infrastructure.
Availability
SIT3921AI-2CF-33NZ125.000000X is available at Aetrix Electronics and suitable for SONET/SDH line cards, satellite modem assemblies, and broadband access gateways requiring stable component supply, long-lifecycle assurance, and consistent parametric performance across production batches.
Supply support for SIT3921AI-2CF-33NZ125.000000X 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
SiTime Corporation is a fabless semiconductor company specializing in MEMS-based timing solutions, headquartered in Sunnyvale, CA, and serving global communications, industrial, and aerospace markets since 2003.
The SiT3921 product line delivers digitally controlled differential oscillators optimized for high-reliability, low-jitter applications in telecom infrastructure, test equipment, and satellite systems where quartz alternatives lack programmability or stability.
FAQ
What output signaling type does the SIT3921AI-2CF-33NZ125.000000X use?
The SIT3921AI-2CF-33NZ125.000000X uses LVDS (Low-Voltage Differential Signaling) output with 200–500 mV differential swing, 1.125–1.375 V common-mode voltage, and 360–600 ps rise/fall times. This matches standard LVDS receivers and eliminates the need for external level-shifting or termination resistors beyond the standard 100 Ω load.
What is the absolute pull range (APR) of the SIT3921AI-2CF-33NZ125.000000X?
The SIT3921AI-2CF-33NZ125.000000X has a nominal pull range of ±1600 ppm and frequency stability of ±10 ppm. Its absolute pull range (APR) is ±1585 ppm, calculated as APR = PR − F_stab − F_aging (1600 − 10 − 5), ensuring usable tuning margin after accounting for aging and initial tolerance.
How is frequency updated on the SIT3921AI-2CF-33NZ125.000000X?
Frequency is updated via the DP pin using a 40-bit serial frame (16-bit header + 8-bit address + 16-bit data). In Mode 2-used for ±1600 ppm range-the update requires two frames (LSW to address 0x07, MSW to 0x06), with final frequency change occurring only after the second frame completes, achieving 12.5 kSPS maximum update rate.
Does the SIT3921AI-2CF-33NZ125.000000X require external configuration on power-up?
No. The SIT3921AI-2CF-33NZ125.000000X starts up at its factory-programmed 125.000000 MHz frequency with default register values (all zeros), placing output at the center of the ±1600 ppm control range. No host initialization or configuration sequence is needed for basic operation.
What package size and footprint does the SIT3921AI-2CF-33NZ125.000000X use?
The SIT3921AI-2CF-33NZ125.000000X uses a 5.0 mm × 3.2 mm × 0.75 mm 6-pin ceramic surface-mount package (order code "C"). Its land pattern follows JEDEC MO-220 standards with 1.40 mm pad pitch, 0.65 mm pad width, and 2.25 mm overall length-compatible with standard SMT assembly processes.
SIT3921AI-2CF-33NZ125.000000X Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Base Resonator:
- -
- Type:
- -
- Frequency:
- -
- Function:
- -
- Output:
- -
- Voltage - Supply:
- -
- Frequency Stability:
- -
- Absolute Pull Range (APR):
- -
- Operating Temperature:
- -
- Spread Spectrum Bandwidth:
- -
- Current - Supply (Max):
- -
- Ratings:
- -
- Mounting Type:
- -
- Supplier Device Package:
- 4-VDFN (3.2x2.5)
- Size / Dimension:
- -
- Height - Seated (Max):
- -
SIT3921AI-2CF-33NZ125.000000X FAQ
1.How can I place an order for SIT3921AI-2CF-33NZ125.000000X through Aetrix?
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The price and inventory of SIT3921AI-2CF-33NZ125.000000X are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SIT3921AI-2CF-33NZ125.000000X is usually 5 days.
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5.How can I obtain technical support or documentation for SIT3921AI-2CF-33NZ125.000000X?
For technical support, including SIT3921AI-2CF-33NZ125.000000X datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SIT3921AI-2CF-33NZ125.000000X requirements.
6.How does Aetrix verify that SIT3921AI-2CF-33NZ125.000000X is sourced from the original manufacturer or authorized distributors?
All SIT3921AI-2CF-33NZ125.000000X 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 SIT3921AI-2CF-33NZ125.000000X meets industry standards.
7.What is the process for return or replacement of SIT3921AI-2CF-33NZ125.000000X?
All SIT3921AI-2CF-33NZ125.000000X units undergo pre-shipment inspection (PSI). If there is an issue with SIT3921AI-2CF-33NZ125.000000X, 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 SIT3921AI-2CF-33NZ125.000000X part is unused and in its original packaging.
Return procedure for SIT3921AI-2CF-33NZ125.000000X:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SIT3921AI-2CF-33NZ125.000000X Tags
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