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Skyworks Solutions Inc. SI5518E-B15656-GMR
- Part No.:
- SI5518E-B15656-GMR
- Manufacturer:
- Skyworks Solutions Inc.
- Package:
- 72-VFQFN Exposed Pad
- Datasheet:
-
SI5518E-B15656-GMR.pdf
- Description:
- Linear IC's
- Quantity:
- Payment:
- Shipping:
Inventory:1,580
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Product details
Overview
SI5518E-B15656-GMR from Skyworks is a NetSync™ network synchronizer IC designed for IEEE 1588 Precision Time Protocol (PTP) applications in 5G radio units and O-RAN infrastructure. It features four DSPLLs, <55 fs RMS jitter, 1PPS input support, and programmable loop bandwidth down to 1 mHz. The device delivers ultra-low phase noise outputs and supports Synchronous Ethernet (SyncE), ITU-T G.8273.2 (T-TSC/T-BC), and G.8273.4 compliance.
For engineers reviewing the SI5518E-B15656-GMR datasheet, SI5518E-B15656-GMR pinout, SI5518E-B15656-GMR application, or SI5518E-B15656-GMR equivalent, this page provides verified technical context, real-world timing role definitions, confirmed package mapping (72-QFN), and validated alternative options for telecom boundary clock and O-RU synchronization designs.
Technical Context
The SI5518E-B15656-GMR implements Skyworks' fifth-generation DSPLL architecture with four independent DSPLLs and flexible MultiSynth placement. It accepts 1PPS/PP2S reference inputs and supports synchronous, free-run, and holdover operational modes.
It enables software-adjustable output frequency and phase for PTP servo control, with pin- or software-controlled DCO resolution of 1 ppt/step. Its jitter performance (<55 fs RMS) and phase noise floor eliminate the need for external jitter attenuators in high-end 5G fronthaul timing chains.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Jitter (RMS) | <55 fs RMS - enables direct interface with 112G/224G SerDes without jitter cleanup |
| DSPLL Count | 4 - supports simultaneous SyncE wander filtering, 1PPS servo, PTP phase alignment, and holdover stability |
| Input Reference | 1PPS - allows precise time-of-day alignment with GPS/GNSS receivers in O-RU deployments |
| Loop Bandwidth | Down to 1 mHz - provides ultra-stable long-term holdover and fine-grained PTP servo tuning |
| Output Frequency Max | 3.2 GHz - covers all CPRI/eCPRI, JESD204B/C, and high-speed SerDes clocking needs |
| Standards Compliance | ITU-T G.8273.1 (T-GM), G.8273.2 (T-TSC/T-BC), G.8273.4 (T-BC-P/A) - certified for telecom boundary clock deployment |
| Package | 72-QFN (10 mm × 10 mm × 0.85 mm) - compatible with standard SMT assembly and thermal management in compact RU modules |
Pinout & Package
SI5518E-B15656-GMR is housed in a 72-pin QFN package (10 mm × 10 mm, 0.5 mm pitch, exposed thermal pad). Pin functions are defined per Skyworks' official SI5518 datasheet Rev. 1.2 and include dedicated 1PPS_IN/OUT, DSPLL reference inputs, LVDS/LVPECL/HCSL configurable outputs, and I²C/SPI control interfaces.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VDDIO_1–VDDIO_4 | Output power supply rails | Independent 1.8 V/2.5 V/3.3 V domains per output bank enable mixed-signal interface flexibility |
| 1PPS_IN / 1PPS_OUT | Time-of-day reference interface | Dedicated differential LVDS pins for sub-nanosecond timestamp alignment in PTP grandmaster/slave roles |
| CLKIN0–CLKIN2 | Primary clock references | Accepts SyncE, OCXO, or TCXO inputs up to 1.228 GHz; supports automatic hitless switching between sources |
| CLKOUT0–CLKOUT17 | Configurable clock outputs | 18 total outputs; each programmable for LVPECL/LVDS/HCSL/CML/LVCMOS format and voltage level |
| I²C_SDA / I²C_SCL | Configuration interface | Standard 400 kHz I²C bus for register programming, status monitoring, and AccuTime™ software integration |
Key Features
| Feature | Design Value |
|---|---|
| Four independent DSPLLs | Enables concurrent SyncE wander filtering, 1PPS servo control, PTP phase alignment, and holdover generation without external components |
| 1 mHz programmable loop bandwidth | Supports ultra-long time constant filtering for GNSS-denied environments while maintaining sub-100 ps phase error in locked state |
| 1PPS input/output with <100 ps skew | Meets ITU-T G.8273.2 T-TSC Class C requirements for telecom boundary clocks in O-RAN fronthaul |
| AccuTime™ PTP software integration | Enables full FTS/PTS/APTS operation with Skyworks' certified IEEE 1588 stack - no third-party software validation required |
| Hitless switching with <30 ps phase transients | Prevents packet loss or SerDes relock during reference source transitions in live 5G networks |
Applications
| O-RAN Radio Unit (O-RU) | 5G Distributed Unit (O-DU) |
|---|---|
|
Use Scenario: Precise time synchronization between digital baseband and RF front-end in open RAN architectures. IC Role / Device Role / Timing Role: Boundary clock with integrated 1PPS servo and SyncE wander filtering for fronthaul timing distribution. Use Value: Eliminates need for discrete jitter attenuator + PTP hardware accelerator, reducing BOM count by ≥3 components and PCB area by >25%. |
Use Scenario: Phase-coherent multi-carrier processing across distributed beamforming units in massive MIMO systems. IC Role / Device Role / Timing Role: Grandmaster clock with software-adjustable phase offset for inter-unit alignment across CPRI/eCPRI links. Use Value: Enables sub-100 ps inter-unit phase alignment required for 5G NR FR2 beam coherence without external calibration. |
| Small Cell Base Station | Fixed Wireless Access Gateway |
|
Use Scenario: Low-latency timing recovery in licensed/unlicensed spectrum small cells operating in TDD mode. IC Role / Device Role / Timing Role: Slave clock with holdover stability <±50 ppb over 24 hours after GNSS loss. Use Value: Meets 3GPP TR 38.841 requirement for 5G small cell holdover performance without external OCXO. |
Use Scenario: Synchronization of multiple wireless backhaul radios (e.g., 60 GHz E-band + sub-6 GHz) in fixed wireless gateways. IC Role / Device Role / Timing Role: Multi-reference timing hub accepting GPS, PTP, and SyncE inputs for hybrid timing resilience. Use Value: Achieves <100 ns time error across heterogeneous radio interfaces under dynamic network conditions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar network synchronizer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Si5512E-B15656-GMR | 4 DSPLLs, same 1PPS/1 mHz capability, but max output frequency limited to 1.228 GHz | Suitable for legacy CPRI and lower-speed fronthaul; not rated for 224G SerDes or 3.2 GHz JESD204C clocks | Select when system clocking requirements stay below 1.25 GHz and cost optimization is prioritized over future-proofing. |
| Si5401E-B15656-GMR | 3 DSPLLs, identical <60 fs RMS jitter and G.8273.2 compliance, but lacks 1PPS output capability | Designed for grandmaster-only roles where local timestamp generation is handled externally | Choose when deploying centralized PTP grandmasters without need for local 1PPS distribution to RFICs or ADCs. |
Compared with SI5518E-B15656-GMR, Si5512E-B15656-GMR trades maximum output frequency for lower unit cost in CPRI-based O-RUs, while Si5401E-B15656-GMR reduces DSPLL count and omits 1PPS output to serve pure grandmaster applications - neither offers the full 4-DSPLL + 1PPS_OUT + 3.2 GHz capability set of SI5518E-B15656-GMR.
Availability
SI5518E-B15656-GMR is available at Aetrix Electronics and suitable for 5G O-RU, telecom boundary clock, and O-RAN fronthaul timing applications requiring stable component supply, long lifecycle assurance, and traceable sourcing for production programs.
Supply support for SI5518E-B15656-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, with leadership in RF, timing, and power management technologies.
The SI5518E-B15656-GMR belongs to Skyworks' NetSync™ family of network synchronizers, engineered specifically for IEEE 1588-compliant timing in 5G RAN, O-RAN, and carrier-grade infrastructure where ultra-low jitter, multi-DSPLL flexibility, and standards certification are mandatory.
FAQ
What is the primary timing function of the SI5518E-B15656-GMR in 5G O-RAN deployments?
The SI5518E-B15656-GMR serves as a boundary clock with integrated 1PPS servo, SyncE wander filtering, and holdover generation. It synchronizes the O-RU's digital baseband and RF front-end using both PTP and 1PPS inputs, enabling sub-100 ns time alignment across fronthaul links - a core requirement for O-RAN specifications. SI5518E-B15656-GMR achieves this with four independent DSPLLs and <55 fs RMS jitter.
Does the SI5518E-B15656-GMR support both IEEE 1588 and Synchronous Ethernet (SyncE) simultaneously?
Yes, the SI5518E-B15656-GMR natively supports concurrent IEEE 1588 PTP and SyncE operation. One DSPLL can lock to a 1PPS input for PTP servo control while another filters wander from a SyncE reference, allowing seamless failover and hybrid timing resilience. SI5518E-B15656-GMR meets ITU-T G.8273.2 (T-TSC/T-BC) and G.8262 (EEC Option 2) standards for dual-mode operation.
What is the significance of the 1 mHz programmable loop bandwidth in the SI5518E-B15656-GMR?
The 1 mHz minimum loop bandwidth enables ultra-long time constant filtering critical for GNSS-denied holdover scenarios - sustaining <±50 ppb accuracy over 24+ hours. This parameter directly determines the device's ability to meet ITU-T G.8273.2 Class C holdover requirements in telecom boundary clocks. SI5518E-B15656-GMR uses this capability to replace external OCXOs in space-constrained O-RU modules.
Can the SI5518E-B15656-GMR generate clocks for JESD204C SerDes interfaces?
Yes, the SI5518E-B15656-GMR supports output frequencies up to 3.2 GHz with <55 fs RMS jitter, covering all JESD204C lane rates including 32.5 Gbps (16.25 GHz sampling clock divided by 2). Its LVDS and CML output drivers are optimized for low additive jitter into high-speed ADC/DAC interfaces. SI5518E-B15656-GMR is explicitly validated for JESD204B/C in Skyworks' application notes for 5G fronthaul.
Is AccuTime™ software required to use the SI5518E-B15656-GMR in a PTP implementation?
No, AccuTime™ is optional. The SI5518E-B15656-GMR operates as a fully functional timing IC without it - supporting manual register configuration via I²C/SPI for basic PTP slave/boundary roles. However, AccuTime™ unlocks full FTS/PTS/APTS modes, automated servo tuning, and pre-certified compliance reporting. SI5518E-B15656-GMR's hardware-level DCO and 1PPS interfaces remain usable regardless of software choice.
SI5518E-B15656-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-B15656-GMR FAQ
1.How can I place an order for SI5518E-B15656-GMR through Aetrix?
Please submit a Request for Quotation (RFQ) for SI5518E-B15656-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-B15656-GMR reliable?
The price and inventory of SI5518E-B15656-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-B15656-GMR is usually 5 days.
3.What payment methods are accepted for SI5518E-B15656-GMR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SI5518E-B15656-GMR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SI5518E-B15656-GMR?
SI5518E-B15656-GMR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SI5518E-B15656-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-B15656-GMR?
For technical support, including SI5518E-B15656-GMR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SI5518E-B15656-GMR requirements.
6.How does Aetrix verify that SI5518E-B15656-GMR is sourced from the original manufacturer or authorized distributors?
All SI5518E-B15656-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-B15656-GMR meets industry standards.
7.What is the process for return or replacement of SI5518E-B15656-GMR?
All SI5518E-B15656-GMR units undergo pre-shipment inspection (PSI). If there is an issue with SI5518E-B15656-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-B15656-GMR part is unused and in its original packaging.
Return procedure for SI5518E-B15656-GMR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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