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

Skyworks Solutions Inc. SI5512B-B15655-GM

Name: SI5512B-B15655-GM
Brand: Skyworks Solutions Inc.
SKU: SI5512B-B15655-GM
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SI5512B-B15655-GM

Manufacturer:: Skyworks Solutions Inc.

Category:: Clock Generators, PLLs, Frequency Synthesizers

Package:: 72-VFQFN Exposed Pad

Datasheet:: SI5512B-B15655-GM.pdf

Description:: Linear IC's

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Product details

Overview

SI5512B-B15655-GM from Skyworks Solutions is a 12-output network synchronization clock IC supporting IEEE 1588v2, SyncE, and eCPRI for 5G wireless infrastructure. It integrates dual DSPLLs with 1 ppt DCO resolution, RFPLL for CPRI clocks up to 491.52 MHz, and delivers 47 fs RMS jitter at 491.52 MHz. It serves as the primary timing engine on digital boards in split-architecture massive MIMO systems.

For engineers reviewing the SI5512B-B15655-GM datasheet, SI5512B-B15655-GM pinout, SI5512B-B15655-GM application, or SI5512B-B15655-GM equivalent, key selection criteria include ITU-T G.8273.2/G.8273.4 compliance, JESD204B/C DCLK/SYSREF pair support, programmable output delay (±10 ns), and dual-reference jitter attenuation bandwidth (10–4 kHz / 30–4 kHz).

Technical Context

The SI5512B-B15655-GM implements three independent PLL domains: RFPLL for ultra-low-noise RF clock synthesis (–164 dBc/Hz noise floor at 491.52 MHz), two fully featured DSPLLs for Ethernet fronthaul synchronization with adjustable DCO and automatic Free-Run/Holdover/Locked state transitions, and PPSPLL for instant lock to 1PPS/PP2S with 1 mHz–25 mHz loop bandwidth.

It supports six JESD204B/C DCLK/SYSREF output pairs with synchronized phase alignment across devices, integer outputs up to 1.2288 GHz and fractional outputs up to 650 MHz, and configurable output formats including LVDS, LVPECL, HCSL, CML, and slew-rate-limited LVCMOS - all with output-to-output skew ≤ ±50 ps.

Key Specifications

Parameter	Value and Actual Design Meaning
RMS Jitter	47 fs typical (12 kHz–20 MHz, 491.52 MHz carrier) - meets stringent 5G RRU phase noise requirements
Phase Noise Floor	–164 dBc/Hz at 491.52 MHz - enables clean RF signal generation without added spectral contamination
DCO Resolution	1 ppt - provides sub-picosecond phase adjustment for precise IEEE 1588 servo control
Jitter Attenuation BW	10–4 kHz and 30–4 kHz dual-reference modes - allows optimized filtering for SyncE and 1588 traffic profiles
Output Count & Types	12 programmable outputs: DCLK/SYSREF pairs, integer/fractional dividers, LVDS/LVPECL/HCSL/CML/LVCMOS - supports multi-standard fronthaul clocking
Input Support	6 inputs: differential (8 kHz–1 GHz), CMOS (1PPS/PP2S, 8 kHz–250 MHz) - accommodates diverse reference sources including GPS-disciplined oscillators
Compliance	ITU-T G.8273.2 (T-TSC/T-BC), G.8273.4 (T-BC-P/A, T-TSC-P/A), G.8262.1 (eEEC), G.8273.1 (T-GM) - certified for telecom boundary and grandmaster roles

Pinout & Package

SI5512B-B15655-GM is housed in a 72-lead QFN package (10 mm × 10 mm, 0.5 mm pitch) with exposed thermal pad. The package supports –40 °C to +105 °C board temperature operation and is Pb-free/RoHS compliant.

Pin/Terminal	Circuit Role	Design Meaning
VDDA_3P3	Analog core supply	3.3 V supply for RFPLL and DSPLL analog circuitry; requires low-noise decoupling
VDDA_1P8	Analog core supply	1.8 V supply for DCO and phase detector blocks; separate from digital domain
VDDOx (x=1–12)	Output driver supply	Configurable per-output voltage (1.8 V/2.5 V/3.3 V) to match connected PHY interface levels
SDA/SCL or SDO/SCK/SDI/CS	Serial interface	I²C or SPI (3-/4-wire) configuration bus; supports in-system programming and real-time status readback
IN0–IN5	Reference input	Differential or single-ended clock inputs; auto-detects format and locks within milliseconds
OUT0–OUT11	Programmable clock output	Each independently configurable as DCLK, SYSREF, or system clock with ±10 ns static delay and <50 ps skew
LOS/OOF/PHMON	Status monitor output	Open-drain flags indicating loss-of-signal, out-of-frequency, or phase monitor alerts for system diagnostics

Key Features

Feature	Design Value
Zero Delay Mode	All PLLs support zero-delay operation - eliminates fixed latency between input reference and output clocks for deterministic timing paths
Hitless Clock Switching	Automatic or manual input switching with <150 ps phase transient - maintains system timing continuity during reference failover
Programmable Loop Bandwidth	DSPLL: 1 mHz–4 kHz; PPSPLL: 1 mHz–25 mHz - enables adaptive response to network timing variations and holdover stability optimization
AccuTime™ Software Ready	Host-processor-executed IEEE 1588v2 servo + protocol stack - offloads timing critical functions from hardware, reducing BOM cost and design complexity
MultiSynth™ Fractional Synthesis	Generates exact JESD204B/C SYSREF frequencies (e.g., 122.88 MHz, 245.76 MHz) with <–95 dBc spurs - avoids frequency planning compromises

Applications

5G Massive MIMO Digital Board Timing	JESD204B/C Fronthaul Clocking
Use Scenario: Digital baseband board in O-RAN-compliant massive MIMO radio requiring synchronized clocks for FPGA-based beamforming and data transport. IC Role / Device Role / Timing Role: Primary network synchronizer generating 12 low-jitter clocks - six DCLK/SYSREF pairs for ADC/DAC interfaces and six auxiliary clocks for control logic and monitoring. Use Value: Enables deterministic inter-FPGA timing alignment across distributed radio units while meeting 3GPP Release 16 fronthaul jitter limits (<100 fs RMS).	Use Scenario: Wireless remote radio head (RRH) using JESD204B subclass 1 to interface with multiple high-speed ADCs and DACs. IC Role / Device Role / Timing Role: JESD204B/C clock generator providing phase-aligned DCLK and pulsed SYSREF with sub-nanosecond skew across all converters. Use Value: Eliminates SYSREF timing uncertainty during multichip synchronization, ensuring coherent sampling across 64+ antenna elements.
IEEE 1588 Telecom Boundary Clock (T-BC)	eCPRI Fronthaul Timing Recovery
Use Scenario: Centralized unit (CU) in Open RAN architecture acting as ITU-T G.8273.2-compliant boundary clock for downstream DU synchronization. IC Role / Device Role / Timing Role: Dual-DSPLL timing engine locking to PTP grandmaster via SyncE or 1PPS, then distributing traceable time to fronthaul interfaces. Use Value: Achieves <±50 ns time error in slave mode and <±100 ns holdover drift over 24 hours - satisfies O-RAN WG4 timing KPIs.	Use Scenario: Distributed unit (DU) recovering precise timing from eCPRI packetized fronthaul streams for RF processing. IC Role / Device Role / Timing Role: Jitter attenuator and phase-aligner converting recovered eCPRI timestamps into low-phase-noise local clocks for RFICs and transceivers. Use Value: Reduces recovered clock jitter by >30 dB versus direct packet-timestamp recovery - enables 256-QAM modulation at 100 MHz channel bandwidth.

5G Massive MIMO Digital Board Timing

JESD204B/C Fronthaul Clocking

Use Scenario: Digital baseband board in O-RAN-compliant massive MIMO radio requiring synchronized clocks for FPGA-based beamforming and data transport.

IC Role / Device Role / Timing Role: Primary network synchronizer generating 12 low-jitter clocks - six DCLK/SYSREF pairs for ADC/DAC interfaces and six auxiliary clocks for control logic and monitoring.

Use Value: Enables deterministic inter-FPGA timing alignment across distributed radio units while meeting 3GPP Release 16 fronthaul jitter limits (<100 fs RMS).

Use Scenario: Wireless remote radio head (RRH) using JESD204B subclass 1 to interface with multiple high-speed ADCs and DACs.

IC Role / Device Role / Timing Role: JESD204B/C clock generator providing phase-aligned DCLK and pulsed SYSREF with sub-nanosecond skew across all converters.

Use Value: Eliminates SYSREF timing uncertainty during multichip synchronization, ensuring coherent sampling across 64+ antenna elements.

IEEE 1588 Telecom Boundary Clock (T-BC)

eCPRI Fronthaul Timing Recovery

Use Scenario: Centralized unit (CU) in Open RAN architecture acting as ITU-T G.8273.2-compliant boundary clock for downstream DU synchronization.

IC Role / Device Role / Timing Role: Dual-DSPLL timing engine locking to PTP grandmaster via SyncE or 1PPS, then distributing traceable time to fronthaul interfaces.

Use Value: Achieves <±50 ns time error in slave mode and <±100 ns holdover drift over 24 hours - satisfies O-RAN WG4 timing KPIs.

Use Scenario: Distributed unit (DU) recovering precise timing from eCPRI packetized fronthaul streams for RF processing.

IC Role / Device Role / Timing Role: Jitter attenuator and phase-aligner converting recovered eCPRI timestamps into low-phase-noise local clocks for RFICs and transceivers.

Use Value: Reduces recovered clock jitter by >30 dB versus direct packet-timestamp recovery - enables 256-QAM modulation at 100 MHz channel bandwidth.

Equivalent & Alternatives

The following parts are listed as comparable options for similar network synchronization applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
Si5518B-B15655-GM	18-output variant with full RF functionality including VCXO phase noise reference and OSYNC for JESD204B/C Subclass 2 - not present in SI5512B-B15655-GM	Required where RF card-level jitter attenuation and JESD204B/C Subclass 2 timing recovery are needed on same PCB	Select SI5512B-B15655-GM when digital/RF functions are split across boards and RF-specific features are delegated to dedicated RF jitter attenuators
LMK5B33414RGZT	TI device with 4 outputs, integrated 3.1 GHz VCO, and different compliance scope (G.8262 only, no G.8273.4 support); lacks dual DSPLL architecture and AccuTime software compatibility	Suitable for smaller-scale RRUs or non-telecom industrial timing where full ITU-T G.8273.4 partial timing support is not required	Choose SI5512B-B15655-GM for full 5G fronthaul compliance, 12-output density, and field-proven O-RAN deployment track record

Compared with Si5518B-B15655-GM, SI5512B-B15655-GM reduces pin count and power while retaining full G.8273.2/4 compliance and JESD204B/C DCLK/SYSREF capability; versus LMK5B33414RGZT, it delivers higher output count, finer DCO resolution (1 ppt vs 10 ppt), and broader telecom standard coverage - critical for carrier-grade 5G deployments.

Availability

SI5512B-B15655-GM is available at Aetrix Electronics and suitable for 5G remote radio units, IEEE 1588 boundary clock systems, and eCPRI fronthaul timing applications requiring stable component supply, long-term lifecycle assurance, and full ITU-T compliance documentation.

Supply support for SI5512B-B15655-GM 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 is a global semiconductor company specializing in analog and mixed-signal connectivity solutions for wireless infrastructure, mobile, automotive, and IoT markets.

The SI5512B-B15655-GM belongs to Skyworks' NetSync™ family of jitter-attenuating network synchronizers, designed specifically for deterministic, standards-compliant timing in 5G fronthaul, O-RAN, and telecom infrastructure equipment.

FAQ

What is the primary timing architecture implemented in the SI5512B-B15655-GM?

The SI5512B-B15655-GM implements a triple-PLL architecture: one RFPLL for ultra-low-noise CPRI clock synthesis, two independent DSPLLs for IEEE 1588/SyncE network synchronization with 1 ppt DCO resolution, and a dedicated PPSPLL for instant lock to 1PPS/PP2S references. This architecture enables simultaneous high-fidelity RF clocking and precise packet-based time recovery - a core requirement for O-RAN split architectures. All PLLs support Zero Delay Mode and hitless switching.

Does the SI5512B-B15655-GM support JESD204B/C Subclass 2 timing recovery?

No, the SI5512B-B15655-GM does not support JESD204B/C Subclass 2 timing recovery. As stated in the official Skyworks Data Short, it omits OSYNC functionality and VCXO phase noise reference features required for Subclass 2. It fully supports Subclass 0 and Subclass 1, including synchronized DCLK/SYSREF generation and SYSREF pulsing. For Subclass 2 applications, Skyworks recommends the Si5518B-B15655-GM variant instead.

What output voltage levels and logic families does the SI5512B-B15655-GM support?

The SI5512B-B15655-GM supports per-output driver supply voltages of 1.8 V, 2.5 V, or 3.3 V, enabling compatibility with modern low-voltage PHYs. Output logic families include LVDS, S-LVDS, AC-coupled LVPECL, LVCMOS, slew-rate-limited (SRL) LVCMOS, HCSL, and CML. Each of the 12 outputs is independently configurable for format, frequency, and delay - allowing mixed-interface clock distribution on a single device.

How does the SI5512B-B15655-GM achieve compliance with ITU-T G.8273.4 Partial Timing Support?

The SI5512B-B15655-GM achieves G.8273.4 compliance through its dual DSPLL architecture with programmable loop bandwidth (1 mHz–4 kHz), automatic Free-Run/Holdover/Locked state transitions, and phase slope limiting (PSL) for controlled pull-in behavior. Its 1 ppt DCO resolution and low intrinsic jitter (47 fs RMS) ensure time error remains within ±100 ns during holdover - satisfying T-BC-P and T-TSC-P performance thresholds defined in G.8273.4.

Is AccuTime™ IEEE 1588 software included with the SI5512B-B15655-GM?

AccuTime™ IEEE 1588 software is an optional add-on offering for the SI5512B-B15655-GM - not bundled with the silicon. It consists of a host-processor-executed servo algorithm and PTP protocol stack that interfaces with the SI5512B-B15655-GM's DCO via I²C/SPI. Skyworks provides the software separately under license, along with integration support and field-tested compliance reports for G.8273.2 and G.8273.4.

SI5512B-B15655-GM Specifications

Product attributes: Attribute value

Manufacturer:: Skyworks Solutions Inc.

Series:: NetSync™

Package/Case:: 72-VFQFN Exposed Pad

Packaging:: Tray

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:: 6:12

Differential - Input:Output:: Yes/Yes

Frequency - Max:: 650MHz, 1.2288GHz

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)

SI5512B-B15655-GM FAQ

1.How can I place an order for SI5512B-B15655-GM through Aetrix?

Please submit a Request for Quotation (RFQ) for SI5512B-B15655-GM 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 SI5512B-B15655-GM reliable?

The price and inventory of SI5512B-B15655-GM are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SI5512B-B15655-GM is usually 5 days.

3.What payment methods are accepted for SI5512B-B15655-GM?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SI5512B-B15655-GM transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SI5512B-B15655-GM?

SI5512B-B15655-GM orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SI5512B-B15655-GM 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 SI5512B-B15655-GM?

For technical support, including SI5512B-B15655-GM datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SI5512B-B15655-GM requirements.

6.How does Aetrix verify that SI5512B-B15655-GM is sourced from the original manufacturer or authorized distributors?

All SI5512B-B15655-GM 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 SI5512B-B15655-GM meets industry standards.

7.What is the process for return or replacement of SI5512B-B15655-GM?

All SI5512B-B15655-GM units undergo pre-shipment inspection (PSI). If there is an issue with SI5512B-B15655-GM, 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 SI5512B-B15655-GM part is unused and in its original packaging.

Return procedure for SI5512B-B15655-GM:

1.Submit a request within 90 days.

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

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