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

Skyworks Solutions Inc. SI5351A-B05268-GT

Name: SI5351A-B05268-GT
Brand: Skyworks Solutions Inc.
SKU: SI5351A-B05268-GT
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SI5351A-B05268-GT

Manufacturer:: Skyworks Solutions Inc.

Category:: Clock Generators, PLLs, Frequency Synthesizers

Package:: -

Datasheet:: SI5351A-B05268-GT.pdf

Description:: I2C PROG, ANY FREQUENCY, ANY OUT

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Product details

Overview

SI5351A-B05268-GT from Skyworks Solutions is an I²C-programmable, 8-output CMOS clock generator with integrated VCXO, designed to replace crystals, crystal oscillators, and discrete PLLs in cost-sensitive embedded systems. It delivers up to eight independent, non-integer-related frequencies from 2.5 kHz to 200 MHz with 0 ppm synthesis error, operates from a 25/27 MHz crystal, and supports 1.8/2.5/3.3 V output voltage levels per bank for mixed-signal timing in audio/video equipment and networking gear.

For engineers reviewing the SI5351A-B05268-GT datasheet, SI5351A-B05268-GT pinout, SI5351A-B05268-GT application, or SI5351A-B05268-GT equivalent, this device offers factory-preprogrammed configuration, low period jitter (<70 ps pk-pk), glitchless frequency changes, programmable rise/fall times, and static phase offset control - all critical for PCIe Gen 1–compliant clocking and multi-domain synchronization.

Technical Context

The SI5351A-B05268-GT implements a dual-PLL architecture (PLLA + PLLB) with high-resolution MultiSynth fractional dividers per output, enabling independent frequency synthesis on all eight outputs. Its input stage accepts only a fixed-frequency crystal (25 or 27 MHz) - no CLKIN or VC pins are functional - and uses internal load capacitance (0–10 pF selectable) to eliminate external crystal tuning components.

Each output features separate VDDO supply pins (VDDOA–VDDOD), supporting level translation across 1.8 V, 2.5 V, or 3.3 V logic families. Spread spectrum modulation is configurable per output (down-spread: –0.1% to –2.5%; center-spread: ±0.1% to ±1.5%), and output drive strength is set via register-controlled 50 Ω impedance for optimal signal integrity at up to 200 MHz.

Key Specifications

Parameter	Value and Actual Design Meaning
Output count	8 independent CMOS clock outputs (CLK0–CLK7)
Frequency range	2.5 kHz to 200 MHz per output; two unique frequencies >112.5 MHz allowed simultaneously
Frequency accuracy	0 ppm synthesis error - eliminates need for post-fabrication trimming or calibration
Period jitter	<70 ps pk-pk (typical, all outputs active, 20-QFN package)
Supply flexibility	Core VDD: 2.5 V or 3.3 V; four independent VDDO banks: 1.8/2.5/3.3 V selectable per bank
Crystal reference	25 MHz or 27 MHz AT-cut crystal only - no external CLKIN or VC support
I²C interface	Standard/Fast Mode (100/400 kbps); supports A0 address pin for multi-device bus

Pinout & Package

SI5351A-B05268-GT is housed in a 20-pin QFN (4 mm × 4 mm, 0.5 mm pitch) with exposed thermal pad. Pin functions are validated per Skyworks Si5351A 20-pin QFN pinout specification (Rev. 1.3, Section 10.1).

Pin/Terminal	Circuit Role	Design Meaning
XA / XB	Crystal oscillator input	Connects to 25/27 MHz AT-cut crystal; internal load capacitance configurable (0/6/8/10 pF)
SCL / SDA	I²C serial interface	Configures device registers; supports multi-drop bus via A0 pin (pin 1)
CLK0–CLK7	Dedicated CMOS clock outputs	Each routed to independent VDDO supply (VDDOA–VDDOD) for mixed-voltage system interfacing
VDDOA–VDDOD	Output buffer supply rails	Four independent 1.8/2.5/3.3 V supplies - enables simultaneous LVCMOS18/LVCMOS25/LVCMOS33 outputs
OEB	Output enable (active-low)	Glitch-free global disable of all clocks; supports power-aware sequencing
A0	I²C address select	Configures LSB of I²C slave address (0x60 or 0x61) for up to two devices on same bus
GND / VDD / EPAD	Ground, core supply, thermal pad	EPAD must be soldered to PCB ground plane for thermal performance (θJA = 74.9°C/W, 2-layer board)

Key Features

Feature	Design Value
Factory preprogrammed configuration	Eliminates runtime I²C initialization - device powers up with verified clock plan immediately
Per-output spread spectrum	Reduces EMI at specific frequencies without affecting system timing margins
Static phase offset control	Enables precise inter-output skew alignment (333 ps/step resolution) for DDR or SerDes clocking
Programmable rise/fall time	Adjusts edge rates to match trace impedance and minimize reflections on long clock nets
Glitchless frequency transitions	Ensures uninterrupted clock delivery during dynamic reconfiguration - critical for live video/audio systems

Applications

Audio/Video Timing	Networking Equipment
Use Scenario: Generating synchronized pixel clocks (74.25 MHz), audio master clocks (24.576 MHz), and HDMI TMDS clocks (148.5 MHz) in AV receivers and streaming boxes. IC Role / Device Role / Timing Role: Single-chip multi-domain clock source replacing 3+ discrete oscillators and buffers. Use Value: Reduces BOM count and layout area while maintaining <70 ps period jitter across all domains.	Use Scenario: Providing reference clocks for Ethernet PHYs (25 MHz), switch fabric controllers (125 MHz), and USB 3.0 transceivers (100 MHz) in residential gateways. IC Role / Device Role / Timing Role: I²C-configurable clock hub delivering PCIe Gen 1–compliant clocks with spread spectrum enabled on noise-sensitive links. Use Value: Eliminates crystal matching tolerances and enables single-point firmware update of all timing parameters.
Industrial Instrumentation	Laser Range Finders
Use Scenario: Driving ADC sampling clocks (10–100 MHz), FPGA logic clocks, and display refresh signals in handheld test meters. IC Role / Device Role / Timing Role: Low-power, multi-voltage clock generator supporting 1.8 V sensor interfaces and 3.3 V microcontroller domains. Use Value: Independent VDDO rails allow direct connection to mixed-voltage peripherals without level shifters.	Use Scenario: Generating precise trigger pulses (1–10 MHz) and time-of-flight measurement clocks (125 MHz) in compact laser distance sensors. IC Role / Device Role / Timing Role: Factory-programmed clock source with static phase offset for sub-nanosecond pulse alignment. Use Value: 0 ppm synthesis error ensures consistent timebase accuracy across temperature and unit-to-unit variation.

Audio/Video Timing

Networking Equipment

Use Scenario: Generating synchronized pixel clocks (74.25 MHz), audio master clocks (24.576 MHz), and HDMI TMDS clocks (148.5 MHz) in AV receivers and streaming boxes.

IC Role / Device Role / Timing Role: Single-chip multi-domain clock source replacing 3+ discrete oscillators and buffers.

Use Value: Reduces BOM count and layout area while maintaining <70 ps period jitter across all domains.

Use Scenario: Providing reference clocks for Ethernet PHYs (25 MHz), switch fabric controllers (125 MHz), and USB 3.0 transceivers (100 MHz) in residential gateways.

IC Role / Device Role / Timing Role: I²C-configurable clock hub delivering PCIe Gen 1–compliant clocks with spread spectrum enabled on noise-sensitive links.

Use Value: Eliminates crystal matching tolerances and enables single-point firmware update of all timing parameters.

Industrial Instrumentation

Laser Range Finders

Use Scenario: Driving ADC sampling clocks (10–100 MHz), FPGA logic clocks, and display refresh signals in handheld test meters.

IC Role / Device Role / Timing Role: Low-power, multi-voltage clock generator supporting 1.8 V sensor interfaces and 3.3 V microcontroller domains.

Use Value: Independent VDDO rails allow direct connection to mixed-voltage peripherals without level shifters.

Use Scenario: Generating precise trigger pulses (1–10 MHz) and time-of-flight measurement clocks (125 MHz) in compact laser distance sensors.

IC Role / Device Role / Timing Role: Factory-programmed clock source with static phase offset for sub-nanosecond pulse alignment.

Use Value: 0 ppm synthesis error ensures consistent timebase accuracy across temperature and unit-to-unit variation.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
Si5351B-B-GM	Includes functional VC pin for voltage-controlled tuning; supports 0–240 ppm pull range	Required where system-level frequency adjustment (e.g., network synchronization) is needed	Select when VCXO functionality is mandatory; SI5351A-B05268-GT lacks VC pin and cannot tune
Si5351C-B-GM	Accepts external CLKIN (10–100 MHz); synchronizes outputs to external reference	Necessary for designs requiring lock to GPS-disciplined or telecom line references	Choose when external reference locking is required; SI5351A-B05268-GT only supports crystal reference

Compared with SI5351B-B-GM and SI5351C-B-GM, SI5351A-B05268-GT provides lowest-cost, crystal-only operation with identical 8-output capability and jitter performance - ideal for fixed-frequency, free-running applications where VC or CLKIN inputs add unnecessary complexity and cost.

Availability

SI5351A-B05268-GT is available at Aetrix Electronics and suitable for audio/video equipment, networking/communication infrastructure, and industrial instrumentation requiring stable component supply, factory-programmed reliability, and long-term timing consistency.

Supply support for SI5351A-B05268-GT 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, broadband, automotive, and industrial markets.

The Si5351A/B/C family was engineered to replace discrete timing components - crystals, oscillators, VCXOs, and PLLs - with a single, software-configurable IC that reduces design complexity, BOM cost, and board space in resource-constrained embedded systems.

FAQ

What is the reference input requirement for SI5351A-B05268-GT?

The SI5351A-B05268-GT requires a 25 MHz or 27 MHz fundamental-mode AT-cut crystal connected to XA/XB pins. It does not support external CLKIN or VC inputs - those functions are exclusive to Si5351B and Si5351C variants. Internal load capacitance (0/6/8/10 pF) is programmable to match crystal specifications without external capacitors.

Does SI5351A-B05268-GT support spread spectrum clocking?

Yes, SI5351A-B05268-GT supports per-output spread spectrum modulation with selectable down-spread (–0.1% to –2.5%) or center-spread (±0.1% to ±1.5%) profiles. Modulation rate is fixed at 31.5 kHz. This feature is configured via I²C registers and helps reduce electromagnetic interference in noise-sensitive applications like audio/video systems.

What is the maximum output frequency supported by SI5351A-B05268-GT?

The SI5351A-B05268-GT supports output frequencies from 2.5 kHz to 200 MHz. However, only two unique frequencies above 112.5 MHz may be generated simultaneously (e.g., 125 MHz and 130 MHz). Multiple outputs can replicate the same high-frequency signal - for example, four outputs at 125 MHz and four at 130 MHz - but three distinct frequencies >112.5 MHz are not permitted.

How is power supply decoupling implemented for SI5351A-B05268-GT?

SI5351A-B05268-GT requires separate decoupling for VDD (core) and each VDDO bank (VDDOA–VDDOD). Skyworks recommends 100 nF ceramic capacitors placed within 2 mm of each VDDO pin and a 1 µF bulk capacitor near the VDD pin. The device's excellent PSRR eliminates need for ferrite beads or LC filters, simplifying power delivery in space-constrained layouts.

Is SI5351A-B05268-GT pin-compatible with other Si5351 variants?

SI5351A-B05268-GT shares the same 20-pin QFN package and pinout as Si5351B and Si5351C variants in the same package option. However, unused pins (VC on Si5351A, CLKIN on Si5351A) must remain unconnected or tied to GND per datasheet guidance. No PCB changes are needed for mechanical replacement, but electrical compatibility depends on functional requirements - SI5351A-B05268-GT lacks VC and CLKIN functionality.

SI5351A-B05268-GT Specifications

Product attributes: Attribute value

Manufacturer:: Skyworks Solutions Inc.

Series:: *

Package/Case:: -

Packaging:: Tube

Product Status:: Active

Programmable:: Not Verified

Type:: -

PLL:: -

Input:: -

Output:: -

Number of Circuits:: -

Ratio - Input:Output:: -

Differential - Input:Output:: -

Frequency - Max:: -

Divider/Multiplier:: -

Voltage - Supply:: -

Operating Temperature:: -

Mounting Type:: -

Grade:: -

Qualification:: -

Supplier Device Package:: -

SI5351A-B05268-GT FAQ

1.How can I place an order for SI5351A-B05268-GT through Aetrix?

Please submit a Request for Quotation (RFQ) for SI5351A-B05268-GT 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 SI5351A-B05268-GT reliable?

The price and inventory of SI5351A-B05268-GT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SI5351A-B05268-GT is usually 5 days.

3.What payment methods are accepted for SI5351A-B05268-GT?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SI5351A-B05268-GT transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SI5351A-B05268-GT?

SI5351A-B05268-GT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SI5351A-B05268-GT 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 SI5351A-B05268-GT?

For technical support, including SI5351A-B05268-GT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SI5351A-B05268-GT requirements.

6.How does Aetrix verify that SI5351A-B05268-GT is sourced from the original manufacturer or authorized distributors?

All SI5351A-B05268-GT 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 SI5351A-B05268-GT meets industry standards.

7.What is the process for return or replacement of SI5351A-B05268-GT?

All SI5351A-B05268-GT units undergo pre-shipment inspection (PSI). If there is an issue with SI5351A-B05268-GT, 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 SI5351A-B05268-GT part is unused and in its original packaging.

Return procedure for SI5351A-B05268-GT:

1.Submit a request within 90 days.

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

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