Skyworks Solutions Inc. SI5338B-B03800-GM

Overview

SI5338B-B03800-GM from Skyworks Solutions is an I²C-programmable quad clock generator IC with four independently configurable differential or single-ended outputs, 0.7 ps RMS typical phase jitter, PCIe Gen 1–4 Common Clock and Gen 3 SRNS compliance, and operation from 1.8/2.5/3.3 V core supply. It replaces up to four crystal oscillators in high-speed serial interface timing applications such as PCIe switch cards and FPGA-based compute platforms.

For engineers reviewing the SI5338B-B03800-GM datasheet, SI5338B-B03800-GM pinout, SI5338B-B03800-GM application, or SI5338B-B03800-GM equivalent, key selection considerations include its MultiSynth™ fractional-N synthesis architecture, per-output voltage configuration (1.5–3.3 V), independent phase/frequency adjustment (±45 ns / 1 ppm steps), and support for LVPECL/LVDS/HCSL/CMOS/SSTL/HSTL output formats across 0.16–710 MHz.

Technical Context

The SI5338B-B03800-GM implements a two-stage PLL architecture: a high-stability integer-N Phase-Locked Loop (Stage 1) locks to one of six input references (crystal, CMOS, SSTL/HSTL, or differential), followed by four independent MultiSynth™ fractional-N synthesis blocks (Stage 2) generating each output. Each MultiSynth supports integer or fractional mode with <1 ppb frequency resolution and programmable initial phase offset (±45 ns).

Its output stage provides per-driver supply voltage selection (VDDO0–VDDO3), independent enable control (OEB), glitchless frequency increment/decrement via dedicated pins or I²C, and configurable spread-spectrum clocking (0.5–5.0% spread, 33–63 kHz modulation rate). Loss-of-lock and loss-of-signal alarms are reported on the INTR pin.

Key Specifications

Pinout & Package

SI5338B-B03800-GM uses a 24-pin QFN package (4 × 4 mm, 0.5 mm pitch) with exposed thermal pad. Pin assignments are fixed per the Si5338 family: inputs (IN1–IN6), outputs (CLK0A/B through CLK3A/B), power (VDD, VDDO0–VDDO3), control (SCL, SDA, INTR, OEB), and ground (GND, RSVD_GND).

Key Features

Applications

Equivalent & Alternatives

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

Compared with Si5338A-B03800-GM, the SI5338B-B03800-GM offers identical hardware but ships with factory-tuned NVM settings for faster time-to-operation; versus ICS8430I-01LG, it delivers full programmability, lower jitter, and multi-voltage/multi-format flexibility at the cost of configuration overhead.

Availability

SI5338B-B03800-GM is available at Aetrix Electronics and suitable for PCIe switch timing, FPGA clocking, Ethernet synchronization, and broadcast video timing requiring stable component supply and long-term industrial availability.

Supply support for SI5338B-B03800-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 was designed specifically for high-performance, software-configurable clock generation in datacenter, telecom, and broadcast systems where low jitter, multi-output flexibility, and PCIe compliance are mandatory.

FAQ

What is the primary function of the SI5338B-B03800-GM in a system design?

The SI5338B-B03800-GM serves as a programmable quad clock generator that synthesizes up to four independent, low-jitter output frequencies from a single input reference. Its core function is to replace multiple discrete oscillators or clock sources while enabling precise phase alignment, spread-spectrum control, and mixed-signal interface support-making it ideal for PCIe, FPGA, and high-speed serial timing applications. The SI5338B-B03800-GM integrates patented MultiSynth™ technology to deliver true zero-ppm frequency accuracy on all outputs.

Does the SI5338B-B03800-GM support PCIe Gen 4 timing requirements?

Yes, the SI5338B-B03800-GM is explicitly validated for PCIe Gen 4 Common Clock mode with ≤0.45 ps RMS jitter (10 kHz–50 MHz) and meets the PCI-SIG specification under defined test conditions (100 MHz HCSL outputs, PLL bandwidth 2–5 MHz). It also complies with PCIe Gen 3 SRNS and earlier generations. Validation is documented in Skyworks' AN562 and supported by the free Skyworks PCIe Clock Jitter Tool for system-level verification of the SI5338B-B03800-GM.

How many different output voltage levels can be configured simultaneously on the SI5338B-B03800-GM?

The SI5338B-B03800-GM supports four independent output buffer supply rails (VDDO0–VDDO3), each configurable for 1.5 V, 1.8 V, 2.5 V, or 3.3 V. This allows simultaneous operation of outputs at different logic voltages-for example, driving 1.8 V LVDS SerDes receivers and 3.3 V CMOS control logic from the same SI5338B-B03800-GM device-without external level shifters.

Can the SI5338B-B03800-GM generate non-integer-related output frequencies?

Yes, the SI5338B-B03800-GM uses fractional-N MultiSynth™ synthesis to generate any frequency within its specified range (0.16–710 MHz) with <1 ppb resolution, regardless of integer relationships to the input reference. Unlike integer-N PLLs, it does not require harmonically related inputs and supports arbitrary frequency combinations-e.g., 125.000123 MHz and 156.250456 MHz simultaneously-making the SI5338B-B03800-GM suitable for heterogeneous timing architectures.

Is external programming hardware required to configure the SI5338B-B03800-GM?

No, the SI5338B-B03800-GM is fully configurable via its onboard I²C/SMBus interface using standard system microcontrollers or host processors. Skyworks' ClockBuilder Pro software generates register configuration files that can be loaded at power-up or dynamically during operation. The SI5338B-B03800-GM includes factory-programmed OTP NVM, so basic functionality is available immediately after power-on without external programming hardware.