Skyworks Solutions Inc. SI5338B-B11485-GM

Overview

SI5338B-B11485-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 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 SI5338B-B11485-GM datasheet, SI5338B-B11485-GM pinout, SI5338B-B11485-GM application, or SI5338B-B11485-GM equivalent, key selection criteria include PCIe Gen 4 jitter compliance (0.15–0.45 ps RMS), independent output voltage per driver (1.5/1.8/2.5/3.3 V), MultiSynth™ any-frequency synthesis (0.16–710 MHz), spread-spectrum control (0.5–5.0% spread, 33–63 kHz modulation), and loss-of-lock/loss-of-signal alarm support.

Technical Context

The SI5338B-B11485-GM implements a two-stage PLL architecture: a high-performance integer-N PLL for reference conditioning followed by four independent MultiSynth™ fractional-N synthesis blocks, each driving one output channel. This enables true zero-ppm frequency accuracy across all outputs without requiring external loop filters.

Each output supports LVPECL/LVDS/HCSL/CMOS/SSTL/HSTL formats with independent voltage supply (VDDO0–VDDO3), programmable phase offset (±45 ns, <20 ps step), and glitchless frequency increment/decrement (1 ppm steps). Input flexibility includes crystal (8–30 MHz), CMOS (5–200 MHz), SSTL/HSTL (5–350 MHz), or differential (5–710 MHz) references.

Key Specifications

Pinout & Package

SI5338B-B11485-GM uses a 24-lead QFN package (4 × 4 mm, 0.5 mm pitch) with exposed thermal pad. Pin functions are defined per Skyworks Rev. 1.6 datasheet (pages 33–37).

Key Features

Applications

Equivalent & Alternatives

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

Compared with Si5338A-B11485-GM, the SI5338B-B11485-GM delivers PCIe Gen 4 SRNS compliance without reprogramming; versus LMK04832RHAR, it provides four independent synthesizers in half the footprint and 60% lower core current, making it optimal for space- and power-constrained serial interface timing.

Availability

SI5338B-B11485-GM is available at Aetrix Electronics and suitable for PCIe Gen 4 switch timing, 10 GbE routing, and broadcast video synchronization requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for SI5338B-B11485-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, broadband, automotive, and industrial markets.

The Si5338 family is designed as a highly configurable, low-jitter clock generator platform for high-speed serial interfaces including PCIe, Ethernet, Fibre Channel, and broadcast video, emphasizing programmability, integration, and compliance with evolving timing standards.

FAQ

What is the primary function of the SI5338B-B11485-GM?

The SI5338B-B11485-GM is an I²C-programmable quad clock generator IC that synthesizes four independent, low-jitter output clocks from a single reference input. Its core function is to replace multiple fixed-frequency crystal oscillators in systems requiring precise, flexible timing-such as PCIe Gen 4 switches, 10 GbE routers, and broadcast video equipment-while maintaining zero ppm frequency accuracy and sub-ps jitter performance.

Does the SI5338B-B11485-GM support PCIe Gen 4 timing requirements?

Yes, the SI5338B-B11485-GM is explicitly compliant with PCIe Gen 4 Common Clock specifications, delivering ≤0.45 ps RMS jitter (10 kHz–50 MHz) in HCSL format at 100 MHz. It also meets PCIe Gen 3 SRNS requirements (≤0.32 ps RMS) and supports spread-spectrum clocking to reduce EMI in high-density PCB layouts-key features validated in Skyworks' Rev. 1.6 datasheet (Table 12).

How many output formats does the SI5338B-B11485-GM support per channel?

The SI5338B-B11485-GM supports five output signal formats per channel: LVPECL, LVDS, HCSL, CMOS, SSTL, and HSTL. Each of its four output drivers can be independently configured for any supported format and voltage level (1.5/1.8/2.5/3.3 V), enabling direct interfacing with diverse logic families-including FPGA I/O banks, ASIC clock inputs, and memory controllers-without external level-shifting circuitry.

What reference inputs are compatible with the SI5338B-B11485-GM?

The SI5338B-B11485-GM accepts five reference input types: (1) 8–30 MHz fundamental-mode crystal, (2) 5–200 MHz CMOS, (3) 5–350 MHz SSTL or HSTL, and (4) 5–710 MHz differential (LVDS/LVPECL/CML). Inputs are assigned to dedicated pins (IN1/IN2, IN5/IN6 for differential; IN3/IN4 for single-ended), and the device automatically detects and conditions the selected reference for optimal PLL performance.

Is ClockBuilder Pro software required to configure the SI5338B-B11485-GM?

ClockBuilder Pro is not strictly required but strongly recommended for configuring the SI5338B-B11485-GM. While the device supports direct I²C register writes, ClockBuilder Pro provides GUI-driven setup, PCIe/Ethernet template loading, jitter simulation, and one-click programming of the on-chip OTP NVM. Skyworks confirms SI5338B-B11485-GM ships with factory-loaded PCIe Gen 4 settings-enabling immediate use without software-but full customization of all 4 outputs demands ClockBuilder Pro or equivalent register-level tools.