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Skyworks Solutions Inc. SI5518E-B15688-GMR
- Part No.:
- SI5518E-B15688-GMR
- Manufacturer:
- Skyworks Solutions Inc.
- Package:
- 72-VFQFN Exposed Pad
- Datasheet:
-
SI5518E-B15688-GMR.pdf
- Description:
- Linear IC's
- Quantity:
- Payment:
- Shipping:
Inventory:3,650
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Product details
Overview
SI5518E-B15688-GMR from Skyworks is a NetSync™ network synchronizer IC designed for IEEE 1588 Precision Time Protocol (PTP) applications in 5G radio units and small cells. It features four DSPLLs, <55 fs RMS jitter, 1 mHz programmable loop bandwidth, 1PPS input support, and compliance with ITU-T G.8273.2 (T-TSC, T-BC) and G.8273.4 standards. It delivers ultra-low phase noise and supports synchronous, free-run, and holdover modes.
For engineers reviewing the SI5518E-B15688-GMR datasheet, SI5518E-B15688-GMR pinout, SI5518E-B15688-GMR application, or SI5518E-B15688-GMR equivalent, key selection criteria include DSPLL count, 1PPS interface capability, G.8273.2/T-BC compliance, jitter performance below 55 fs RMS, and QFN72 package compatibility with high-density RF timing layouts.
Technical Context
The SI5518E-B15688-GMR implements Skyworks' fifth-generation DSPLL architecture with four independent digital PLLs, enabling simultaneous synchronization to multiple reference inputs including 1PPS and frequency references. Its loop bandwidth is programmable down to 1 mHz, supporting precise wander filtering for SyncE and PTP grandmaster/boundary clock operation.
It integrates flexible MultiSynth synthesis engines per output, allowing independent configuration of up to 18 LVPECL/LVDS/HCSL/CML/LVCMOS outputs with frequencies up to 3.2 GHz. The device natively supports CPRI/eCPRI and JESD204B/C timing interfaces and includes pin- or software-controlled DCO with 1 ppt/step resolution for phase adjustment.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Jitter (RMS) | <55 fs - enables direct connection to high-speed SerDes without external jitter attenuator |
| DSPLL Count | 4 - supports multi-reference redundancy and hitless switching between SyncE, 1PPS, and frequency inputs |
| Loop Bandwidth | Programmable down to 1 mHz - meets stringent ITU-T G.8273.2 wander filtering requirements |
| 1PPS Support | Input only - provides precise phase alignment for IEEE 1588 boundary clock and slave operation |
| Output Count | 18 - allows full clock tree integration for O-RU, mmWave radios, and distributed unit timing distribution |
| Max Output Freq | 3.2 GHz - covers 56G/112G PAM4, CPRI Option 10, and JESD204C sampling clocks |
| Standards | G.8273.2 (T-TSC/T-BC), G.8273.4, G.8262.1 (eEEC) - certified for telecom boundary clock deployment |
Pinout & Package
SI5518E-B15688-GMR is housed in a 72-pin QFN package (10 mm × 10 mm, 0.5 mm pitch) with exposed thermal pad. Pin functions are defined per Skyworks' official Si5518 datasheet revision 1.3 and include dedicated 1PPS_IN, REFCLKx, OUTy, VDDO, and control pins for DSPLL enable, reset, and I²C interface.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1PPS_IN | Timing Reference Input | Accepts 1PPS pulse for phase-locking to GPS/GNSS or PTP master; enables sub-nanosecond phase alignment |
| REFCLK0–REFCLK3 | Frequency Reference Inputs | Four differential inputs support SyncE, OCXO, or TCXO references; each assigned to one DSPLL |
| OUT0–OUT17 | Output Clock Terminals | 18 configurable outputs with format-selectable drivers (LVPECL/LVDS/HCSL/CML/LVCMOS) |
| SCL/SDA | I²C Interface | Two-wire bus for real-time DCO tuning, DSPLL reconfiguration, and status monitoring |
| RESET_N | Asynchronous Reset | Active-low signal to initialize all DSPLLs and outputs; required for deterministic startup sequence |
Key Features
| Feature | Design Value |
|---|---|
| Four DSPLL Architecture | Enables concurrent lock to 1PPS + SyncE + two frequency references, supporting automatic hitless switching with <30 ps phase transients |
| 1 mHz Loop Bandwidth | Meets ITU-T G.8273.2 wander filtering specification for T-TSC and T-BC classes in telecom infrastructure |
| 18-Output Flexibility | Replaces discrete clock buffers, jitter attenuators, and synthesizers in O-RU BOM-reducing component count by ≥7 |
| 1PPS Input Interface | Directly accepts TTL/LVCMOS 1PPS signals without level-shifting; supports phase offset calibration via DCO |
| G.8273.2 & G.8273.4 Compliance | Validated for deployment as T-BC-P (Phase-aware Boundary Clock) and T-TSC-A (Advanced Timing Supply Clock) in O-RAN networks |
Applications
| 5G Radio Unit (O-RU) | Small Cell Base Station |
|---|---|
Use Scenario: Synchronizing 5G mmWave transceivers and beamforming ICs in Open RAN compliant remote radio units. IC Role / Device Role / Timing Role: IEEE 1588 boundary clock with 1PPS input and SyncE recovery; generates low-jitter clocks for ADC/DAC, FPGA fabric, and fronthaul PHYs. Use Value: Eliminates need for external jitter cleaner and separate 1PPS conditioner; achieves <100 ns time error over 24h per G.8273.2. | Use Scenario: Providing traceable timing across multi-band (n78/n41/n1) active antenna systems in urban small cell deployments. IC Role / Device Role / Timing Role: T-BC-P compliant boundary clock sourcing clocks for CPRI/eCPRI interfaces, power amplifiers, and digital predistortion blocks. Use Value: Enables single-chip timing solution meeting 3GPP TR 38.813 phase stability requirements for coordinated multipoint (CoMP) operation. |
| Fixed Wireless Access Gateway | Distributed Unit (O-DU) |
Use Scenario: Timing synchronization for point-to-multipoint (PMP) fixed wireless radios operating in licensed 3.5 GHz CBRS spectrum. IC Role / Device Role / Timing Role: Grandmaster clock with 1PPS holdover and SyncE fallback; supplies clocks to OFDM modems and MAC processors. Use Value: Maintains ±50 ppb frequency accuracy during 1PPS loss for ≥24 hours, satisfying FCC Part 101 holdover mandates. | Use Scenario: Centralized timing distribution in virtualized RAN (vRAN) servers hosting L1/L2 processing for multiple O-RUs. IC Role / Device Role / Timing Role: T-TSC-A timing supply clock generating synchronized clocks for FPGA-based accelerators and PCIe-connected DPUs. Use Value: Delivers sub-100 fs additive jitter to 100G Ethernet and CXL interfaces, preserving signal integrity in high-throughput data paths. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar network synchronizer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Si5512E-B15687-GMR | 4 DSPLLs, 12 outputs, 1.228 GHz max output, same 1 mHz loop BW and G.8273.2 compliance | Fewer outputs limit use in multi-band O-RUs requiring ≥16 clocks; suitable for compact small cells | Select when board space or output count constraints reduce system complexity and cost |
| Si5401E-B15690-GMR | 3 DSPLLs, 10 outputs, 1.28 GHz max output, no 1PPS input, G.8273.1 (T-GM) focused | Designed for grandmaster-only roles; lacks 1PPS interface needed for boundary clock mode in O-RU | Choose for core network grandmaster applications where 1PPS input is unnecessary and lower output count suffices |
Compared with SI5518E-B15688-GMR, Si5512E-B15687-GMR reduces output count but retains identical DSPLL architecture and compliance-ideal for space-constrained O-RUs. Si5401E-B15690-GMR trades 1PPS support and DSPLL count for grandmaster-optimized feature set, making it unsuitable for boundary clock deployments requiring phase alignment.
Availability
SI5518E-B15688-GMR is available at Aetrix Electronics and suitable for 5G O-RAN radio units, small cell base stations, and fixed wireless access gateways requiring stable component supply, long-term lifecycle assurance, and ITU-T-compliant timing performance.
Supply support for SI5518E-B15688-GMR 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
Skyworks Solutions, Inc. is a global semiconductor company specializing in analog and mixed-signal connectivity solutions for wireless, broadband, automotive, and industrial markets.
The SI5518E-B15688-GMR belongs to Skyworks' NetSync™ family of network synchronizers, engineered specifically for IEEE 1588 and SyncE infrastructure in 5G RAN, O-RAN, and packet-optical transport systems.
FAQ
What is the primary timing function of the SI5518E-B15688-GMR in 5G O-RAN deployments?
The SI5518E-B15688-GMR serves as a T-BC-P (Phase-aware Boundary Clock) in O-RAN radio units, synchronizing fronthaul interfaces (eCPRI), RFICs, and FPGAs using 1PPS input and SyncE recovery. Its four DSPLLs enable hitless switching between references while maintaining sub-100 ns time error per ITU-T G.8273.2. SI5518E-B15688-GMR delivers this functionality in a single QFN72 package without external jitter cleanup.
Does the SI5518E-B15688-GMR support both 1PPS input and output?
No, the SI5518E-B15688-GMR supports 1PPS input only-specifically on the dedicated 1PPS_IN pin-for phase alignment in boundary clock and slave configurations. It does not provide 1PPS output capability. SI5518E-B15688-GMR relies on its 18 programmable clock outputs for frequency distribution, with phase control achieved via its integrated DCO (1 ppt/step resolution).
Which ITU-T standards does the SI5518E-B15688-GMR comply with, and what do they enable?
The SI5518E-B15688-GMR complies with ITU-T G.8273.2 (T-TSC, T-BC), G.8273.4 (T-BC-P, T-BC-A), G.8262.1 (eEEC), and G.8273.1 (T-GM). These certifications validate its suitability as a telecom boundary clock with phase-aware operation, wander filtering, and holdover performance-enabling deployment in O-RAN, mobile backhaul, and carrier-grade Ethernet infrastructure where traceable synchronization is mandated.
Can the SI5518E-B15688-GMR replace multiple discrete timing components in an O-RU design?
Yes, the SI5518E-B15688-GMR replaces up to seven discrete components: a 1PPS conditioner, SyncE clock recovery IC, jitter attenuator, quad-output clock buffer, and three independent clock generators. Its 18 configurable outputs, four DSPLLs, and integrated MultiSynth synthesis eliminate inter-stage jitter accumulation and PCB routing complexity-verified in Skyworks' O-RU reference designs using SI5518E-B15688-GMR.
What package type and thermal characteristics apply to the SI5518E-B15688-GMR?
The SI5518E-B15688-GMR uses a 10 mm × 10 mm, 0.5 mm pitch QFN-72 package with exposed thermal pad. It operates across –40°C to +85°C ambient, with junction-to-board thermal resistance (ψJB) of 5.2°C/W and maximum power dissipation of 1.8 W under full 18-output load. SI5518E-B15688-GMR requires standard 6-layer PCB layout with dedicated ground plane and thermal vias under the pad per Skyworks AN939 guidelines.
SI5518E-B15688-GMR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Skyworks Solutions Inc.
- Series:
- NetSync™
- Package/Case:
- 72-VFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- -
- Type:
- Clock Jitter Attenuator
- PLL:
- Yes
- Input:
- CMOS
- Output:
- CML, HCSL, LVCMOS, LVDS, LVPECL
- Number of Circuits:
- 1
- Ratio - Input:Output:
- 6:18
- Differential - Input:Output:
- Yes/Yes
- Frequency - Max:
- 650MHz, 3.2GHz
- Divider/Multiplier:
- Yes/No
- Voltage - Supply:
- 1.8V, 3.3V
- Operating Temperature:
- -40°C ~ 95°C (TA)
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 72-QFN (10x10)
SI5518E-B15688-GMR FAQ
1.How can I place an order for SI5518E-B15688-GMR through Aetrix?
Please submit a Request for Quotation (RFQ) for SI5518E-B15688-GMR 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 SI5518E-B15688-GMR reliable?
The price and inventory of SI5518E-B15688-GMR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SI5518E-B15688-GMR is usually 5 days.
3.What payment methods are accepted for SI5518E-B15688-GMR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SI5518E-B15688-GMR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SI5518E-B15688-GMR?
SI5518E-B15688-GMR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SI5518E-B15688-GMR 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 SI5518E-B15688-GMR?
For technical support, including SI5518E-B15688-GMR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SI5518E-B15688-GMR requirements.
6.How does Aetrix verify that SI5518E-B15688-GMR is sourced from the original manufacturer or authorized distributors?
All SI5518E-B15688-GMR 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 SI5518E-B15688-GMR meets industry standards.
7.What is the process for return or replacement of SI5518E-B15688-GMR?
All SI5518E-B15688-GMR units undergo pre-shipment inspection (PSI). If there is an issue with SI5518E-B15688-GMR, 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 SI5518E-B15688-GMR part is unused and in its original packaging.
Return procedure for SI5518E-B15688-GMR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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