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Home > Products > Integrated Circuits (ICs) > Clock/Timing > Application Specific Clock/Timing

Skyworks Solutions Inc. SI5338H-B04521-GM

Name: SI5338H-B04521-GM
Brand: Skyworks Solutions Inc.
SKU: SI5338H-B04521-GM
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SI5338H-B04521-GM

Manufacturer:: Skyworks Solutions Inc.

Category:: Application Specific Clock/Timing

Package:: 24-VFQFN Exposed Pad

Datasheet:: SI5338H-B04521-GM.pdf

Description:: I2C CONTROL, 4-OUTPUT, ANY FREQU

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Product details

Overview

SI5338H-B04521-GM from Skyworks Solutions is an I²C-programmable quad clock generator with four independently configurable differential or single-ended outputs, 0.7 ps RMS typical phase jitter, PCIe Gen 1–4 and SRNS compliance, and MultiSynth™ frequency synthesis supporting 0.16–710 MHz output ranges. It replaces up to four crystal oscillators in high-speed networking and FPGA clocking applications.

For engineers reviewing the SI5338H-B04521-GM datasheet, SI5338H-B04521-GM pinout, SI5338H-B04521-GM application, or SI5338H-B04521-GM equivalent, key selection considerations include its 24-QFN package, independent per-output voltage (1.5/1.8/2.5/3.3 V), spread-spectrum capability (0.5–5.0% down-spread), phase adjustment resolution (<20 ps), and I²C/SMBus programmability with ClockBuilder Pro support.

Technical Context

The SI5338H-B04521-GM implements a two-stage PLL architecture: a reference-stage PLL locks to one of six input sources (crystal, CMOS, SSTL/HSTL, or differential), followed by four independent MultiSynth™ fractional-N synthesizers - each driving a dedicated output stage. This enables true zero-ppm frequency accuracy across all four outputs simultaneously.

Each output supports LVPECL/LVDS/HCSL/CMOS/SSTL/HSTL formats with independent supply voltage selection (VDDO0–VDDO3), programmable initial phase offset (±45 ns), and glitchless frequency increment/decrement in 1 ppm steps. The device operates over –40 to +85 °C with core supply options at 1.8 V, 2.5 V, or 3.3 V.

Key Specifications

Parameter	Value and Actual Design Meaning
Phase Jitter (RMS)	0.7 ps - meets PCIe Gen 3/4 common clock and SRNS requirements for high-speed serial links
Output Frequency Range	0.16–710 MHz - covers Ethernet (125/156.25 MHz), PCIe (100 MHz), Fibre Channel (1.0625 GHz ÷ 2 = 531.25 MHz), and processor clocks
Input Reference Support	Crystal (8–30 MHz), CMOS (5–200 MHz), SSTL/HSTL (5–350 MHz), differential (5–710 MHz) - enables flexible system-level clock tree design
Output Formats	LVPECL, LVDS, HCSL, CMOS, SSTL, HSTL - allows direct interface to FPGAs, ASICs, SerDes, and memory controllers without level-shifting
Supply Voltages	VDD core: 1.8/2.5/3.3 V; VDDOx per output: 1.5/1.8/2.5/3.3 V - supports mixed-voltage SoC/FPGA platforms
Package	24-pin QFN, 4 × 4 mm - space-efficient footprint compatible with high-density PCB layouts and automated assembly
Operating Temperature	–40 to +85 °C - qualified for industrial and telecom line card environments

Pinout & Package

SI5338H-B04521-GM is housed in a 24-lead, 4 × 4 mm QFN package with exposed thermal pad. Pin assignments are fixed per the Si5338 family and validated for this variant.

Pin/Terminal	Circuit Role	Design Meaning
IN1/IN2, IN5/IN6	Differential input pairs	Accept 5–710 MHz differential clock references; require external 100 Ω termination
IN3/IN4	Single-ended CMOS/SSTL/HSTL inputs	Support 5–350 MHz single-ended clocks; VIH/VIL thresholds scale with VDD
CLK0A/CLK0B – CLK3A/CLK3B	Differential output pairs	Four independent outputs; each configurable for LVPECL/LVDS/HCSL/CML with dedicated VDDO supply
VDDO0–VDDO3	Output buffer supplies	Enable per-output voltage selection (1.5/1.8/2.5/3.3 V) for mixed-signal interface compatibility
SCL/SDA	I²C interface	Standard SMBus-compatible 2-wire bus for configuration, status readback, and dynamic reprogramming
INTR	Interrupt output	Open-drain alarm signal indicating loss-of-lock or loss-of-signal events
VDD	Core supply	Accepts 1.8 V (±5%), 2.5 V (±10%), or 3.3 V (±10%) with 45 mA typical current draw at 100 MHz output load
GND / RSVD_GND	Ground connections	Multiple GND pins and reserved ground pad ensure low-impedance return path and thermal dissipation

Key Features

Feature	Design Value
Independent MultiSynth™ synthesis per output	Enables simultaneous generation of four unrelated frequencies (e.g., 125 MHz + 156.25 MHz + 312.5 MHz + 625 MHz) with zero ppm error
Programmable spread spectrum	Configurable down-spread (0.5–5.0%) and modulation rate (33–63 kHz) on any output to reduce EMI in dense PCB layouts
Glitchless frequency tuning	Hardware-supported ±1 ppm frequency step updates via PINC/FDEC pins without output interruption or phase discontinuity
Per-output phase adjustment	Sub-20 ps resolution phase offset control per output enables precise timing alignment across multi-lane SerDes or DDR interfaces
Zero-delay mode support	External feedback path allows synchronous clock forwarding with minimal propagation delay - critical for deterministic latency in packet processing

Applications

Ethernet Switch Timing	PCIe Gen 4 Clocking
Use Scenario: 10 GbE/25 GbE switch fabric requiring synchronized 156.25 MHz and 312.5 MHz clocks across multiple PHYs and MACs. IC Role / Device Role / Timing Role: Quad clock generator providing four low-jitter, phase-aligned outputs - two for SerDes lanes and two for management subsystems. Use Value: Eliminates need for multiple discrete oscillators; 0.7 ps RMS jitter ensures compliance with IEEE 802.3bj and 802.3by jitter budgets.	Use Scenario: Server motherboard with dual x16 PCIe Gen 4 slots, requiring 100 MHz common clock plus separate reference for CDR circuits. IC Role / Device Role / Timing Role: PCIe-compliant clock source delivering 100 MHz HCSL to root complex and endpoints, plus auxiliary 100 MHz for retimer ICs. Use Value: Meets PCIe Gen 4 SRNS RMS jitter limit (≤0.45 ps) and supports spread-spectrum to pass FCC Class B emissions testing.
FPGA-Based Video Processing	Telecom Line Card Synchronization
Use Scenario: Broadcast video encoder using Xilinx Ultrascale+ FPGA with multiple clock domains: 148.5 MHz (SMPTE), 297 MHz (dual-link), 74.25 MHz (HD), and 27 MHz (legacy). IC Role / Device Role / Timing Role: Any-frequency clock synthesizer generating four precisely related video clocks from a single 25 MHz crystal reference. Use Value: Achieves <20 ps inter-output skew and ±45 ns programmable phase offsets to align pixel sampling across parallel data paths.	Use Scenario: OTN/SONET line card needing synchronization to 155.52 MHz (OC-3), 622.08 MHz (OC-12), and 2488.32 MHz (OC-48) derived from a 19.44 MHz master clock. IC Role / Device Role / Timing Role: Frequency translator converting telecom-grade reference into multiple SONET/SDH line rates with OC-12 compliant jitter performance. Use Value: 0.7 ps RMS jitter at 155.52 MHz satisfies Telcordia GR-1244-CORE requirement for SDH equipment clocks.

Ethernet Switch Timing

PCIe Gen 4 Clocking

Use Scenario: 10 GbE/25 GbE switch fabric requiring synchronized 156.25 MHz and 312.5 MHz clocks across multiple PHYs and MACs.

IC Role / Device Role / Timing Role: Quad clock generator providing four low-jitter, phase-aligned outputs - two for SerDes lanes and two for management subsystems.

Use Value: Eliminates need for multiple discrete oscillators; 0.7 ps RMS jitter ensures compliance with IEEE 802.3bj and 802.3by jitter budgets.

Use Scenario: Server motherboard with dual x16 PCIe Gen 4 slots, requiring 100 MHz common clock plus separate reference for CDR circuits.

IC Role / Device Role / Timing Role: PCIe-compliant clock source delivering 100 MHz HCSL to root complex and endpoints, plus auxiliary 100 MHz for retimer ICs.

Use Value: Meets PCIe Gen 4 SRNS RMS jitter limit (≤0.45 ps) and supports spread-spectrum to pass FCC Class B emissions testing.

FPGA-Based Video Processing

Telecom Line Card Synchronization

Use Scenario: Broadcast video encoder using Xilinx Ultrascale+ FPGA with multiple clock domains: 148.5 MHz (SMPTE), 297 MHz (dual-link), 74.25 MHz (HD), and 27 MHz (legacy).

IC Role / Device Role / Timing Role: Any-frequency clock synthesizer generating four precisely related video clocks from a single 25 MHz crystal reference.

Use Value: Achieves <20 ps inter-output skew and ±45 ns programmable phase offsets to align pixel sampling across parallel data paths.

Use Scenario: OTN/SONET line card needing synchronization to 155.52 MHz (OC-3), 622.08 MHz (OC-12), and 2488.32 MHz (OC-48) derived from a 19.44 MHz master clock.

IC Role / Device Role / Timing Role: Frequency translator converting telecom-grade reference into multiple SONET/SDH line rates with OC-12 compliant jitter performance.

Use Value: 0.7 ps RMS jitter at 155.52 MHz satisfies Telcordia GR-1244-CORE requirement for SDH equipment clocks.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
Si5338A-B04521-GM	Same pinout and register map; differs only in factory-programmed NVM configuration - A-grade calibrated for wider temperature range (–40 to +105 °C)	Targeted at automotive or extended-temperature industrial use; not required for standard commercial/industrial applications	Select SI5338H-B04521-GM for cost-optimized designs operating strictly within –40 to +85 °C ambient.
LMK04832ISQE/NOPB	Two PLLs + eight outputs; higher power (120 mA); supports JESD204B deterministic latency; no integrated crystal driver	Better suited for JESD204B converter timing and ultra-low-skew multi-device synchronization; requires external VCXO	Choose LMK04832 when deterministic latency, sub-ps skew across >4 outputs, or JESD204B SYSREF generation is required.

Compared with Si5338A-B04521-GM, the SI5338H-B04521-GM offers identical functionality at lower cost for standard temperature applications; versus LMK04832, it provides lower power and integrated crystal support but fewer outputs and no JESD204B features.

Availability

SI5338H-B04521-GM is available at Aetrix Electronics and suitable for Ethernet switch/router, PCIe Gen 4 server boards, and broadcast video timing applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for SI5338H-B04521-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 leader in analog and mixed-signal semiconductors, specializing in RF, timing, and connectivity solutions for infrastructure, automotive, and mobile markets.

The Si5338 product line delivers highly configurable, low-jitter clock generation for high-speed digital systems - designed specifically to replace multiple discrete oscillators and simplify clock tree architecture in networking, computing, and telecom equipment.

FAQ

What is the primary function of the SI5338H-B04521-GM in a system design?

The SI5338H-B04521-GM serves as an I²C-programmable quad clock generator that synthesizes up to four independent, low-jitter output frequencies from a single reference input. Its core function is to replace multiple discrete oscillators while enabling precise frequency, phase, and format control - critical for synchronizing FPGAs, SerDes blocks, and processors in high-speed digital systems. The SI5338H-B04521-GM integrates MultiSynth™ technology to achieve true zero-ppm accuracy across all outputs.

Does the SI5338H-B04521-GM support PCIe Gen 4 Common Clock compliance?

Yes, the SI5338H-B04521-GM is explicitly specified for PCIe Gen 4 Common Clock operation with ≤0.45 ps RMS jitter (10 kHz–50 MHz) when configured for 100 MHz HCSL output and appropriate PLL bandwidth (2–5 MHz). It also meets PCIe Gen 3 SRNS requirements and includes built-in spread-spectrum capability to aid EMI reduction - both validated per PCI-SIG specifications and measured using the Skyworks PCIe Clock Jitter Tool.

Can the SI5338H-B04521-GM generate different output voltage levels on each channel?

Yes, the SI5338H-B04521-GM supports independent output supply voltages via VDDO0 through VDDO3 pins, allowing each of its four output drivers to be set to 1.5 V, 1.8 V, 2.5 V, or 3.3 V. This enables direct interfacing with mixed-voltage devices - for example, driving 1.8 V LVDS SerDes inputs while supplying 3.3 V CMOS logic on the same board - without external level shifters. The SI5338H-B04521-GM's per-output voltage control is configured via I²C registers.

How is the SI5338H-B04521-GM programmed and configured?

The SI5338H-B04521-GM is programmed via a standard I²C/SMBus-compatible 2-wire interface (SCL/SDA pins), with full register access for frequency, format, voltage, phase, and spread-spectrum settings. Configuration is simplified using Skyworks' ClockBuilder Pro software, which generates custom configuration files and supports real-time validation. Factory-programmed NVM retains settings across power cycles, and the SI5338H-B04521-GM supports dynamic reprogramming during operation without interrupting outputs.

What package type and thermal characteristics does the SI5338H-B04521-GM have?

The SI5338H-B04521-GM uses a 24-lead QFN package measuring 4 mm × 4 mm with an exposed thermal pad. Its thermal resistance is θJA = 37 °C/W (still air) and θJC = 10 °C/W, enabling reliable operation at full load within the –40 to +85 °C ambient range. The SI5338H-B04521-GM's low 45 mA typical core supply current minimizes self-heating, and the QFN footprint supports standard reflow profiles including JEDEC J-STD-020 (peak 260 °C).

SI5338H-B04521-GM Specifications

Product attributes: Attribute value

Manufacturer:: Skyworks Solutions Inc.

Series:: MultiSynth™

Package/Case:: 24-VFQFN Exposed Pad

Packaging:: Tray

Product Status:: Active

Programmable:: Not Verified

PLL:: -

Main Purpose:: -

Input:: -

Output:: -

Number of Circuits:: -

Ratio - Input:Output:: -

Differential - Input:Output:: -

Frequency - Max:: -

Voltage - Supply:: -

Operating Temperature:: -

Mounting Type:: Surface Mount

Grade:: -

Qualification:: -

Supplier Device Package:: 24-QFN (4x4)

SI5338H-B04521-GM FAQ

1.How can I place an order for SI5338H-B04521-GM through Aetrix?

Please submit a Request for Quotation (RFQ) for SI5338H-B04521-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 SI5338H-B04521-GM reliable?

The price and inventory of SI5338H-B04521-GM are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SI5338H-B04521-GM is usually 5 days.

3.What payment methods are accepted for SI5338H-B04521-GM?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SI5338H-B04521-GM transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SI5338H-B04521-GM?

SI5338H-B04521-GM orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SI5338H-B04521-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 SI5338H-B04521-GM?

For technical support, including SI5338H-B04521-GM datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SI5338H-B04521-GM requirements.

6.How does Aetrix verify that SI5338H-B04521-GM is sourced from the original manufacturer or authorized distributors?

All SI5338H-B04521-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 SI5338H-B04521-GM meets industry standards.

7.What is the process for return or replacement of SI5338H-B04521-GM?

All SI5338H-B04521-GM units undergo pre-shipment inspection (PSI). If there is an issue with SI5338H-B04521-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 SI5338H-B04521-GM part is unused and in its original packaging.

Return procedure for SI5338H-B04521-GM:

1.Submit a request within 90 days.

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

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