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Home > Products > Integrated Circuits (ICs) > Clock/Timing > Clock Generators, PLLs, Frequency Synthesizers

Skyworks Solutions Inc. SI5508C-B15717-GMR

Name: SI5508C-B15717-GMR
Brand: Skyworks Solutions Inc.
SKU: SI5508C-B15717-GMR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SI5508C-B15717-GMR

Manufacturer:: Skyworks Solutions Inc.

Category:: Clock Generators, PLLs, Frequency Synthesizers

Package:: 72-VFQFN Exposed Pad

Datasheet:: SI5508C-B15717-GMR.pdf

Description:: SI5508C-B15717-GMR

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Product details

Overview

SI5508C-B15717-GMR from Skyworks is a low-phase-noise, jitter-attenuating clock IC for 5G/eCPRI fronthaul systems. It integrates a high-performance RFPLL and two MultiSynth™ fractional dividers, delivers up to 18 configurable outputs (including JESD204B/C DCLK/SYSREF pairs), achieves 47 fs RMS jitter at 491.52 MHz, and supports integer outputs to 3.2 GHz and fractional outputs to 650 MHz.

For engineers reviewing the SI5508C-B15717-GMR datasheet, SI5508C-B15717-GMR pinout, SI5508C-B15717-GMR application, or SI5508C-B15717-GMR equivalent, key selection criteria include jitter performance (<47 fs RMS), JESD204B/C synchronization capability across multiple devices, programmable output delay (±10 ns), selectable jitter attenuation bandwidth (10 Hz–4 kHz), and support for LVDS/LVPECL/HCSL/CML/LVCMOS output formats.

Technical Context

The SI5508C-B15717-GMR implements Skyworks' fifth-generation DSPLL™ architecture, combining frequency synthesis and jitter attenuation in a single digital PLL without external loop filter components. Its RFPLL generates ultra-low-jitter CPRI clocks for remote radio heads, while dual MultiSynth™ fractional dividers enable flexible, independent synthesis of any output from either path.

It supports automatic mode switching between Free-Run, Holdover, and Locked states using a fixed-frequency XO/XTAL reference; optional VCXO input enables highest phase noise performance. Input clock switching is hitless (<150 ps phase transient), and all 18 outputs feature programmable static delay and skew control (±50 ps).

Key Specifications

Parameter	Value and Actual Design Meaning
RMS Jitter	47 fs typical (12 kHz–20 MHz integration band, 491.52 MHz carrier)
Phase Noise Floor	–164 dBc/Hz at 491.52 MHz carrier
Integer Output Max	3.2 GHz - supports high-speed SerDes and RF sampling clocks
Fractional Output Max	650 MHz - enables precise SYSREF and auxiliary system clock generation
JESD204B/C Support	Subclass 0/1/2 with synchronized DCLK/SYSREF pairs across multiple devices
Output Delay Range	±10 ns per output - allows fine-grained timing alignment in multi-device systems
Input Frequency Range	Differential: 8 kHz–1 GHz; CMOS: 8 kHz–250 MHz - accommodates diverse reference sources

Pinout & Package

SI5508C-B15717-GMR is housed in a 72-lead QFN package (10 mm × 10 mm, 0.5 mm pitch) with exposed thermal pad. The package meets JEDEC MO-220 outline and supports –40 °C to +105 °C board-level operation.

Pin/Terminal	Circuit Role	Design Meaning
VDDO1–VDDO8	Output driver supply rails	Independent 1.8 V / 2.5 V / 3.3 V supplies per output bank - enables mixed-voltage interface support
CLKIN1–CLKIN6	Differential or CMOS clock inputs	Eight total inputs (4 differential pairs or 6 CMOS); auto-detects format and enables hitless switching
OUT0–OUT17	Programmable clock outputs	18 LVDS/S-LVDS/LVPECL/HCSL/CML/LVCMOS outputs with per-pin delay, slew rate, and format control
SCL/SDA or SCLK/MOSI/MISO/SS	Serial interface	I²C or SPI (3-/4-wire) configuration interface - used with ClockBuilder Pro™ for register programming
LOS/OOF/PHMON/FLOL/PLOL	Status monitor outputs	Real-time fault detection signals for loss-of-signal, out-of-frequency, phase monitor, and lock status

Key Features

Feature	Design Value
Fifth-gen DSPLL™ core	Eliminates external loop filter components and reduces BOM count while maintaining sub-50 fs jitter
MultiSynth™ fractional synthesis	Enables independent, glitch-free fractional clock generation on any output without shared divider constraints
JESD204B/C SYSREF pulser mode	Generates deterministic, aligned SYSREF pulses for multi-converter synchronization without external logic
Zero Delay Mode	Configures output to replicate input timing with minimal added latency - critical for fronthaul latency budgets
DCO adjust resolution	1 ppt (parts-per-trillion) frequency tuning step - supports ultra-fine frequency calibration in closed-loop systems

Applications

5G Remote Radio Units (RRU)	JESD204B/C Clock Generation
Use Scenario: Timing synchronization between FPGA-based baseband processors and high-speed ADC/DACs in compact 5G RRUs. IC Role / Device Role / Timing Role: Primary jitter-attenuating clock generator providing synchronized DCLK and SYSREF pairs to multiple converters. Use Value: Enables deterministic multi-device alignment with <47 fs jitter, meeting JESD204C Subclass 2 timing margins under variable temperature and voltage.	Use Scenario: High-density data converter subsystems requiring multiple independent, phase-aligned clock domains. IC Role / Device Role / Timing Role: Centralized clock source generating up to nine DCLK/SYSREF pairs with inter-pair skew <50 ps. Use Value: Eliminates need for discrete clock buffers and external delay tuning, reducing PCB area and signal integrity risk.
Mobile Fronthaul Networks	eCPRI-Based Small Cells
Use Scenario: Ethernet-based fronthaul links between centralized unit (CU) and distributed unit (DU) in Open RAN architectures. IC Role / Device Role / Timing Role: Jitter cleaner and frequency translator converting recovered eCPRI reference into low-jitter CPRI-compatible clocks. Use Value: Maintains <100 ns phase error over temperature via holdover stability and automatic free-run mode during reference loss.	Use Scenario: Indoor picocells and outdoor small cells where space, power, and thermal constraints limit component count. IC Role / Device Role / Timing Role: Single-chip timing solution delivering all required clocks (BB, RF, SYSREF, management) from one reference. Use Value: Reduces bill-of-materials by consolidating eight+ discrete oscillators and buffers into one 10×10 mm QFN device.

5G Remote Radio Units (RRU)

JESD204B/C Clock Generation

Use Scenario: Timing synchronization between FPGA-based baseband processors and high-speed ADC/DACs in compact 5G RRUs.

IC Role / Device Role / Timing Role: Primary jitter-attenuating clock generator providing synchronized DCLK and SYSREF pairs to multiple converters.

Use Value: Enables deterministic multi-device alignment with <47 fs jitter, meeting JESD204C Subclass 2 timing margins under variable temperature and voltage.

Use Scenario: High-density data converter subsystems requiring multiple independent, phase-aligned clock domains.

IC Role / Device Role / Timing Role: Centralized clock source generating up to nine DCLK/SYSREF pairs with inter-pair skew <50 ps.

Use Value: Eliminates need for discrete clock buffers and external delay tuning, reducing PCB area and signal integrity risk.

Mobile Fronthaul Networks

eCPRI-Based Small Cells

Use Scenario: Ethernet-based fronthaul links between centralized unit (CU) and distributed unit (DU) in Open RAN architectures.

IC Role / Device Role / Timing Role: Jitter cleaner and frequency translator converting recovered eCPRI reference into low-jitter CPRI-compatible clocks.

Use Value: Maintains <100 ns phase error over temperature via holdover stability and automatic free-run mode during reference loss.

Use Scenario: Indoor picocells and outdoor small cells where space, power, and thermal constraints limit component count.

IC Role / Device Role / Timing Role: Single-chip timing solution delivering all required clocks (BB, RF, SYSREF, management) from one reference.

Use Value: Reduces bill-of-materials by consolidating eight+ discrete oscillators and buffers into one 10×10 mm QFN device.

Equivalent & Alternatives

The following parts are listed as comparable options for similar jitter-attenuating clock generator applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
LMK5B33414RGZT	Four independent PLLs, higher integration of LDOs, lower max integer output (2.5 GHz), no VCXO option	Better suited for multi-domain industrial clock trees; lacks eCPRI-optimized holdover and hitless switching	Prefer when system requires internal power regulation and four isolated synthesis paths over eCPRI-specific robustness
AD9545BCPZ	Four DDS-based DPLLs, higher flexibility in fractional synthesis, 300 fs RMS jitter (worse than SI5508C-B15717-GMR), no integrated RFPLL	Stronger for multi-reference, adaptive timing recovery; weaker for fixed low-jitter wireless fronthaul	Choose when dynamic reference switching and ultra-fine frequency resolution outweigh absolute jitter floor requirements

Compared with LMK5B33414RGZT and AD9545BCPZ, the SI5508C-B15717-GMR delivers superior jitter performance (47 fs vs. ≥300 fs), native eCPRI/CPRI holdover behavior, and integrated RFPLL architecture optimized for wireless fronthaul - making it the preferred choice for 5G RRH and small-cell timing where phase noise and deterministic synchronization are critical.

Availability

SI5508C-B15717-GMR is available at Aetrix Electronics and suitable for 5G remote radio units, JESD204B/C converter timing systems, and eCPRI-based mobile fronthaul networks requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for SI5508C-B15717-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 infrastructure, automotive, and industrial markets.

The Si55xx family was designed specifically for ultra-low-jitter timing in 5G wireless fronthaul and eCPRI systems, integrating DSPLL™ and MultiSynth™ technologies to replace legacy discrete PLL + oscillator + buffer combinations.

FAQ

What is the primary function of the SI5508C-B15717-GMR in 5G systems?

The SI5508C-B15717-GMR serves as a jitter-attenuating clock generator optimized for 5G remote radio head (RRH) and eCPRI fronthaul applications. It synthesizes ultra-low-jitter clocks (47 fs RMS) from noisy or unstable references, provides up to 18 programmable outputs-including synchronized JESD204B/C DCLK and SYSREF pairs-and maintains timing integrity during reference loss via automatic holdover mode. Its RFPLL and MultiSynth™ architecture makes the SI5508C-B15717-GMR essential for meeting strict 5G phase noise and synchronization requirements.

Does the SI5508C-B15717-GMR support JESD204C timing standards?

Yes, the SI5508C-B15717-GMR supports JESD204C Subclass 2 timing through its JESD204B/C DCLK/SYSREF generation capability, including deterministic SYSREF pulsing, inter-device synchronization, and output-to-output skew control (±50 ps). While the datasheet explicitly confirms JESD204B/C Subclass 0/1/2 compliance, its 47 fs RMS jitter, ±10 ns programmable delay, and hitless switching meet JESD204C's tighter jitter and alignment requirements for high-speed converter interfaces. This ensures the SI5508C-B15717-GMR remains viable for next-generation JESD204C deployments.

What package type and thermal specifications apply to the SI5508C-B15717-GMR?

The SI5508C-B15717-GMR uses a 72-lead QFN package measuring 10 mm × 10 mm with 0.5 mm pitch and an exposed thermal pad. It is rated for board-level operating temperatures from –40 °C to +105 °C and ambient temperatures from –40 °C to +95 °C. The package conforms to JEDEC MO-220 outline and includes coplanarity ≤0.08 mm and mold flatness ≤0.1 mm - ensuring reliable reflow assembly and thermal performance in dense 5G base station PCB layouts. These specs are fully validated for the SI5508C-B15717-GMR.

Can the SI5508C-B15717-GMR operate without an external VCXO?

Yes, the SI5508C-B15717-GMR can operate using a standard fixed-frequency crystal oscillator (XO) or crystal (XTAL) as its phase noise reference, enabling Free-Run and Holdover modes without a VCXO. A VCXO input is optional and only required for applications demanding the absolute lowest phase noise (e.g., –145 dBc/Hz at 800 kHz offset). The SI5508C-B15717-GMR automatically locks to valid inputs, enters holdover upon loss, and resumes locked operation seamlessly - making the VCXO unnecessary unless specified by system-level phase noise targets.

How is the SI5508C-B15717-GMR configured during system design?

The SI5508C-B15717-GMR is configured via I²C or SPI interface using Skyworks' ClockBuilder Pro™ (CBPro™) software, which auto-generates register maps, validates timing constraints, and exports configuration files for production programming. All 18 outputs, jitter attenuation bandwidth (10 Hz–4 kHz), DCO tuning, and status monitoring settings are programmable in-circuit. Configuration is non-volatile when stored in external EEPROM or loaded at power-up - ensuring repeatable, validated timing behavior across SI5508C-B15717-GMR units in volume production.

SI5508C-B15717-GMR Specifications

Product attributes: Attribute value

Manufacturer:: Skyworks Solutions Inc.

Series:: DSPLL™, MultiSynth™

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)

SI5508C-B15717-GMR FAQ

1.How can I place an order for SI5508C-B15717-GMR through Aetrix?

Please submit a Request for Quotation (RFQ) for SI5508C-B15717-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 SI5508C-B15717-GMR reliable?

The price and inventory of SI5508C-B15717-GMR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SI5508C-B15717-GMR is usually 5 days.

3.What payment methods are accepted for SI5508C-B15717-GMR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SI5508C-B15717-GMR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SI5508C-B15717-GMR?

SI5508C-B15717-GMR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SI5508C-B15717-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 SI5508C-B15717-GMR?

For technical support, including SI5508C-B15717-GMR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SI5508C-B15717-GMR requirements.

6.How does Aetrix verify that SI5508C-B15717-GMR is sourced from the original manufacturer or authorized distributors?

All SI5508C-B15717-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 SI5508C-B15717-GMR meets industry standards.

7.What is the process for return or replacement of SI5508C-B15717-GMR?

All SI5508C-B15717-GMR units undergo pre-shipment inspection (PSI). If there is an issue with SI5508C-B15717-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 SI5508C-B15717-GMR part is unused and in its original packaging.

Return procedure for SI5508C-B15717-GMR:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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