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Skyworks Solutions Inc. SI5518E-B15685-GMR
- Part No.:
- SI5518E-B15685-GMR
- Manufacturer:
- Skyworks Solutions Inc.
- Package:
- 72-VFQFN Exposed Pad
- Datasheet:
-
SI5518E-B15685-GMR.pdf
- Description:
- Linear IC's
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
SI5518E-B15685-GMR from Skyworks is a NetSync™ network synchronizer IC with dual DSPLL architecture, supporting IEEE 1588 PTP in boundary clock mode, ITU-T G.8273.2 (T-BC) and G.8273.4 (T-BC-P/A) compliance, <55 fs RMS jitter, and 1PPS input/output capability for 5G O-RU and small cell timing applications.
For engineers reviewing the SI5518E-B15685-GMR datasheet, SI5518E-B15685-GMR pinout, SI5518E-B15685-GMR application, or SI5518E-B15685-GMR equivalent, this device delivers ultra-low-jitter synchronization with programmable loop bandwidth down to 1 mHz, hitless switching, and AccuTime™ software integration for full PTP stack deployment or servo-only operation.
Technical Context
The SI5518E-B15685-GMR implements two independent DSPLLs with configurable input sources (1PPS, SyncE, or reference clocks), enabling simultaneous T-BC and T-BC-P operation per ITU-T G.8273.4. Each DSPLL supports programmable loop bandwidth from 1 mHz to 100 Hz and phase transient suppression below 30 ps during hitless switching.
It provides 18 LVDS/LVPECL/HCSL/CML/LVCMOS outputs up to 3.2 GHz, with per-output format and voltage selection, integrated 1PPS generation/processing, and support for free-run, holdover, and synchronous modes - all managed via I²C or SPI interface with ClockBuilder Pro configuration.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Jitter (RMS) | <55 fs RMS - enables direct interface to high-speed SerDes without external jitter attenuator |
| DSPLL Count | 2 - supports concurrent T-BC and T-BC-P roles per G.8273.4 for O-RAN mid-haul/front-haul timing separation |
| Output Count | 18 - drives multiple RFICs, FPGAs, and baseband processors in 5G radio units without external fanout buffers |
| Max Output Freq | 3.2 GHz - covers JESD204B/C sampling clocks, CPRI/eCPRI rates, and local oscillator synthesis |
| Input Support | 1PPS + SyncE + 8 kHz–1.228 GHz references - accommodates GPS-disciplined, PTP-derived, and network-derived timing inputs |
| Loop BW Range | 1 mHz to 100 Hz - allows precise wander filtering per G.8273.2 and fast phase recovery during packet loss |
| Compliance | ITU-T G.8273.1/2/4, G.8262 (EEC Option 1/2), G.8262.1 (eEEC) - certified for telecom-grade timing in O-RU, BBU, and FHGWS deployments |
Pinout & Package
SI5518E-B15685-GMR is housed in a 72-pin QFN package (10 mm × 10 mm, 0.5 mm pitch) with exposed thermal pad. Pin functions include dedicated 1PPS_IN/OUT, REFCLK inputs, differential output banks (LVDS/LVPECL/HCSL), VDDO rails per bank, I²C/SPI control, and power/ground distribution optimized for low-noise timing performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1PPS_IN / 1PPS_OUT | Timing reference interface | Direct connection to GNSS receiver or PTP grandmaster; supports sub-nanosecond edge alignment for phase-coherent synchronization |
| REFCLK[0:1] | Primary/secondary reference input | Dual redundant clock inputs for holdover switchover; accepts LVDS/LVPECL/HCSL with automatic format detection |
| CLKOUT[0:17] | Differential clock outputs | 18 individually configurable outputs; each supports format (LVDS/LVPECL/HCSL/CML/LVCMOS), frequency, and slew rate tuning |
| VDDO[0:5] | Output power supply rails | Six independent VDDO supplies enable mixed-voltage operation (1.8 V/2.5 V/3.3 V) across output banks for multi-chip interconnect |
| SDA / SCL / SCLK / SDIO | I²C/SPI control interface | Configures PLL parameters, DCO step size (1 ppt), and operational mode; supports hot-plug reconfiguration without reset |
Key Features
| Feature | Design Value |
|---|---|
| Dual DSPLL architecture | Enables simultaneous T-BC and T-BC-P operation per G.8273.4, eliminating need for separate boundary and transparent clock ICs in O-RAN deployments |
| 1 mHz programmable loop bandwidth | Meets stringent G.8273.2 wander filtering requirements while maintaining fast phase lock (<100 ms) after network interruption |
| 18-format-flexible outputs | Drives heterogeneous SoCs, RFICs, and FPGAs in same 5G RU without level-shifting components or discrete buffers |
| Integrated 1PPS processing | Supports both input disciplining and output generation with <±50 ps jitter, enabling precise time-of-day alignment across distributed radios |
| AccuTime™ software compatibility | Allows full IEEE 1588 PTP stack implementation or servo-only integration with existing host software, reducing firmware development effort |
Applications
| 5G Radio Unit (O-RU) | O-RAN Front-Haul Gateway Switch (FHGWS) |
|---|---|
Use Scenario: Synchronizing distributed massive MIMO antenna elements in open RAN architecture with strict phase alignment across RF chains. IC Role / Device Role / Timing Role: Boundary clock (T-BC) with 1PPS input from GNSS and SyncE input from fronthaul transport, generating low-jitter clocks for ADC/DAC, JESD204C SerDes, and local oscillators. Use Value: Eliminates external jitter attenuator and reduces BOM count by integrating dual DSPLL, 18 outputs, and 1PPS processing - meeting 3GPP TR 38.803 ±1.5 μs phase error requirement. | Use Scenario: Aggregating timing from multiple O-RUs and distributing synchronized clocks to centralized DU units over Ethernet-based fronthaul. IC Role / Device Role / Timing Role: Transparent clock (T-BC-P) with packet delay measurement and compensation, forwarding PTP messages while regenerating clean clocks for downstream PHYs and MACs. Use Value: Achieves G.8273.4 T-BC-P compliance with <30 ps phase transients during hitless switching, enabling seamless handover between primary/backup timing sources without service interruption. |
| Small Cell Base Station | Fixed Wireless Access (FWA) Radio |
Use Scenario: Providing traceable, low-wander timing in compact outdoor small cells where GNSS reception is intermittent and SyncE is unavailable. IC Role / Device Role / Timing Role: Holdover-optimized boundary clock using internal TCXO backup and adaptive loop bandwidth to maintain G.8273.2 Class C stability (<±4.6 ppm over -30°C to +70°C) for >24 hours. Use Value: Delivers telecom-grade timing continuity without external OCXO or complex calibration, reducing size, power, and cost versus legacy solutions. | Use Scenario: Enabling precise time-synchronized beamforming in millimeter-wave FWA radios deployed in non-line-of-sight urban environments. IC Role / Device Role / Timing Role: Dual-role synchronizer: T-BC for backhaul PTP sync and T-TSC for local oscillator phase alignment across phased-array antennas. Use Value: Supports sub-microsecond inter-antenna phase coherence required for 64-QAM/256-QAM modulation at 28 GHz, directly improving EVM and spectral efficiency. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar network synchronizer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Si5401 | 3 DSPLLs, 10 outputs, max 1.28 GHz output, no 1PPS output capability | Targeted at grandmaster and core switch applications requiring higher DSPLL count but fewer outputs and lower frequency range | Preferred when deploying IEEE 1588 grandmaster clocks in metro/core networks rather than O-RU edge timing |
| Si5348 | 3 DSPLLs, 7 outputs, 95 fs RMS jitter, supports only 8 kHz minimum input frequency | Lacks 1PPS interface and G.8273.4 T-BC-P support; limited to SyncE-only or high-frequency reference inputs | Applicable for enterprise switches or routers needing basic SyncE wander filtering without PTP or GNSS integration |
Compared with SI5518E-B15685-GMR, Si5401 offers greater DSPLL scalability for grandmaster use but lacks 1PPS output and 3.2 GHz capability, while Si5348 provides lower-cost SyncE filtering but cannot meet O-RAN fronthaul timing requirements due to missing 1PPS and T-BC-P functionality.
Availability
SI5518E-B15685-GMR is available at Aetrix Electronics and suitable for 5G O-RU, small cell base stations, and O-RAN front-haul gateway switches requiring stable component supply, long-term lifecycle assurance, and traceable sourcing for telecom infrastructure programs.
Supply support for SI5518E-B15685-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 leader in analog and mixed-signal semiconductors, specializing in RF, mobile, infrastructure, and automotive timing solutions.
The SI5518E-B15685-GMR belongs to Skyworks' NetSync™ family of network synchronizers, designed specifically to replace multi-chip timing solutions in 5G RAN equipment with single-chip IEEE 1588 and SyncE compliance.
FAQ
What is the primary timing standard compliance of the SI5518E-B15685-GMR?
The SI5518E-B15685-GMR is fully compliant with ITU-T G.8273.2 (T-TSC and T-BC), G.8273.4 (T-BC-P and T-BC-A), G.8262 (EEC Options 1 and 2), and G.8262.1 (eEEC). It meets these standards through its dual DSPLL architecture, 1 mHz loop bandwidth, and sub-30 ps phase transients - verified per Skyworks' official qualification reports for telecom infrastructure deployment.
Does the SI5518E-B15685-GMR support both 1PPS input and output simultaneously?
Yes, the SI5518E-B15685-GMR supports concurrent 1PPS input and output operation. Its dedicated 1PPS_IN and 1PPS_OUT pins enable GNSS disciplining while generating phase-aligned time-of-day signals for downstream radios or fronthaul interfaces - a key requirement for O-RAN T-BC-P operation per G.8273.4.
How many independent clock outputs does the SI5518E-B15685-GMR provide, and what formats are supported?
The SI5518E-B15685-GMR provides 18 independently configurable clock outputs. Each output supports LVPECL, LVDS, HCSL, CML, or LVCMOS signaling, with per-output VDDO selection (1.8 V, 2.5 V, or 3.3 V) and programmable slew rate - enabling direct drive of heterogeneous RFICs, FPGAs, and SerDes without external level translation.
Can the SI5518E-B15685-GMR operate in holdover mode, and what stability is guaranteed?
Yes, the SI5518E-B15685-GMR supports holdover mode using its internal temperature-compensated crystal oscillator. When locked to a valid reference, it achieves ±0.1 ppb frequency accuracy; in holdover, it maintains G.8273.2 Class C stability (±4.6 ppm over –30°C to +70°C) for more than 24 hours - validated per Skyworks' characterization data for small cell deployments.
Is AccuTime™ software support required to use the SI5518E-B15685-GMR in a PTP system?
No, AccuTime™ software support is optional. The SI5518E-B15685-GMR can operate as a standalone hardware synchronizer with full IEEE 1588 DCO control via I²C/SPI. AccuTime™ adds full PTP stack capabilities (FTS/PTS/APTS), but the SI5518E-B15685-GMR also supports servo-only integration with third-party PTP stacks - preserving existing firmware investments.
SI5518E-B15685-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-B15685-GMR FAQ
1.How can I place an order for SI5518E-B15685-GMR through Aetrix?
Please submit a Request for Quotation (RFQ) for SI5518E-B15685-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-B15685-GMR reliable?
The price and inventory of SI5518E-B15685-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-B15685-GMR is usually 5 days.
3.What payment methods are accepted for SI5518E-B15685-GMR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SI5518E-B15685-GMR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SI5518E-B15685-GMR?
SI5518E-B15685-GMR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SI5518E-B15685-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-B15685-GMR?
For technical support, including SI5518E-B15685-GMR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SI5518E-B15685-GMR requirements.
6.How does Aetrix verify that SI5518E-B15685-GMR is sourced from the original manufacturer or authorized distributors?
All SI5518E-B15685-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-B15685-GMR meets industry standards.
7.What is the process for return or replacement of SI5518E-B15685-GMR?
All SI5518E-B15685-GMR units undergo pre-shipment inspection (PSI). If there is an issue with SI5518E-B15685-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-B15685-GMR part is unused and in its original packaging.
Return procedure for SI5518E-B15685-GMR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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