Skyworks Solutions Inc. SI5338K-B-GMR

Overview

SI5338K-B-GMR 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 across –40 to +85 °C in a 4 × 4 mm 24-QFN package. It replaces up to four crystal oscillators in high-speed serial interface timing applications.

For engineers reviewing the SI5338K-B-GMR datasheet, SI5338K-B-GMR pinout, SI5338K-B-GMR application, or SI5338K-B-GMR equivalent, key selection criteria include its MultiSynth™-based any-frequency synthesis (0.16–710 MHz per output), independent output voltage support (1.5/1.8/2.5/3.3 V), spread-spectrum capability (0.5–5.0% down-spread), and I²C/SMBus programmability with ClockBuilder Pro software integration.

Technical Context

The SI5338K-B-GMR implements a two-stage PLL architecture: a high-stability reference stage (with external crystal or CMOS/SSTL/differential inputs) feeding a fractional-N MultiSynth™ synthesis stage per output. Each output path includes independent R-divider, M-divider, and P-divider control for precise frequency, phase, and spread-spectrum generation.

It supports flexible input references (8–30 MHz crystal, 5–200 MHz CMOS, 5–350 MHz SSTL/HSTL, 5–710 MHz differential) and output formats including LVPECL (0.16–710 MHz), LVDS (0.16–350 MHz), HCSL (0.16–250 MHz), CMOS (0.16–200 MHz), and SSTL/HSTL (0.16–350 MHz), all with per-output supply voltage selection.

Key Specifications

Pinout & Package

SI5338K-B-GMR is housed in a 24-lead, 4 × 4 mm QFN package with exposed thermal pad. Pin assignments are standardized across Si5338 family variants per Skyworks documentation (Rev. 1.6, p.33–37).

Key Features

Applications

Equivalent & Alternatives

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

Compared with Si5332A-D-GM, SI5338K-B-GMR offers smaller footprint and field-programmability but higher jitter; compared with ICS853S01AGI-01LFT, it provides full frequency agility and advanced features at the cost of higher BOM complexity and configuration effort.

Availability

SI5338K-B-GMR is available at Aetrix Electronics and suitable for PCIe Gen 4 server boards, 10 GbE switching platforms, and broadcast video equipment requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for SI5338K-B-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 is a global semiconductor company specializing in analog and mixed-signal connectivity solutions for wireless, broadband, automotive, and industrial markets.

The Si5338 product line delivers programmable, low-jitter clock generation for high-speed serial interfaces including PCIe, Ethernet, Fibre Channel, and broadcast video, emphasizing flexibility, integration, and signal integrity.

FAQ

What is the maximum output frequency supported by the SI5338K-B-GMR?

The SI5338K-B-GMR supports up to 710 MHz on LVPECL outputs and 350 MHz on LVDS/HCSL/SSTL outputs. For frequencies above 350 MHz, only two unique outputs may operate simultaneously - specifically Fvco/4 and Fvco/6 - as defined in Skyworks' functional description (Rev. 1.6, p.19). This limitation ensures phase noise and jitter performance remain within specification.

Does the SI5338K-B-GMR require an external crystal?

The SI5338K-B-GMR supports both external crystals (8–30 MHz) and external clock inputs (CMOS, SSTL/HSTL, or differential), so an external crystal is optional. When using a crystal, load capacitance must be configured via OTP registers to match the crystal's specified CL (typically 12–13 pF supported, 17–19 pF recommended). The SI5338K-B-GMR does not integrate a crystal.

Can the SI5338K-B-GMR generate different output voltages on each channel?

Yes - the SI5338K-B-GMR provides four independent VDDO supply pins (VDDO0–VDDO3), each configurable for 1.5 V, 1.8 V, 2.5 V, or 3.3 V. This allows simultaneous LVDS (2.5 V), HCSL (1.8 V), and CMOS (3.3 V) outputs without external level shifters, directly matching diverse ASIC, FPGA, or PHY voltage requirements.

How is the SI5338K-B-GMR programmed, and is firmware required?

The SI5338K-B-GMR is programmed via its I²C/SMBus interface using Skyworks' ClockBuilder Pro software, which generates register configuration files and supports in-system programming. No external firmware or microcontroller is required - configuration can be loaded at power-up from internal OTP memory or dynamically updated during operation via I²C writes.

Is the SI5338K-B-GMR compliant with PCIe Gen 4 timing requirements?

Yes - the SI5338K-B-GMR meets PCIe Gen 4 Common Clock jitter requirements (0.15–0.45 ps RMS, 10 kHz–50 MHz band) when configured per Skyworks' application notes (AN562) and using appropriate input references and output formats (e.g., HCSL at 100 MHz). Its PLL bandwidth (1.6–4 MHz) and MultiSynth™ architecture are validated for Gen 4 compliance.