Skyworks Solutions Inc. SI5338B-B11486-GM

Overview

SI5338B-B11486-GM from Skyworks Solutions is a quad-output, I²C-programmable clock generator with MultiSynth™ frequency synthesis. It delivers four independent differential or single-ended clocks (up to 710 MHz LVPECL/LVDS, 350 MHz SSTL/HSTL), 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 - used for FPGA/processor clocking and high-speed serial interface timing.

For engineers reviewing the SI5338B-B11486-GM datasheet, SI5338B-B11486-GM pinout, SI5338B-B11486-GM application, or SI5338B-B11486-GM equivalent, key selection criteria include output format flexibility per channel (LVPECL/LVDS/HCSL/CMOS/SSTL/HSTL), independent voltage per output driver (1.5–3.3 V), ±20 ps phase step resolution, and spread-spectrum control (0.5–5.0% deviation, 33–63 kHz modulation).

Technical Context

The SI5338B-B11486-GM integrates a dual-stage PLL architecture: a high-stability reference stage followed by four independent MultiSynth™ fractional-N synthesizers. Each output path includes configurable dividers (R/M/P), programmable initial phase offset (±45 ns), and glitchless frequency increment/decrement via dedicated pins or I²C.

It supports multiple input references - external crystal (8–30 MHz), CMOS (5–200 MHz), SSTL/HSTL (5–350 MHz), or differential (5–710 MHz) - and enables zero-delay mode via external feedback. Loss-of-lock and loss-of-signal alarms provide real-time status monitoring.

Key Specifications

Pinout & Package

SI5338B-B11486-GM is housed in a 4 × 4 mm, 24-lead QFN package with exposed thermal pad. Pin assignments are fixed per the Si5338 family: IN1/IN2 (differential ref 1), IN3/IN4 (single-ended ref), IN5/IN6 (differential ref 2), CLK0A/CLK0B through CLK3A/CLK3B (four differential output pairs), VDDO0–VDDO3 (independent output supply pins), VDD (core supply), SCL/SDA (I²C interface), INTR (interrupt output), and RSVD_GND (reserved ground).

Key Features

Applications

Equivalent & Alternatives

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

Compared with Si5338A-B11486-GM and LMK04832ISQE/NOPB, SI5338B-B11486-GM provides superior integration density (4×4 mm), lower jitter (0.7 ps RMS), and finer-grained output control (per-pin VDDO, phase step <20 ps), making it optimal for space-constrained, multi-protocol timing applications where PCIe and SerDes jitter budgets are tight.

Availability

SI5338B-B11486-GM is available at Aetrix Electronics and suitable for processor/FPGA clocking, PCIe Gen 1–4 timing, and broadcast video/audio synchronization requiring stable component supply, long-term lifecycle support, and consistent electrical performance across temperature.

Supply support for SI5338B-B11486-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 product line was designed as a highly flexible, software-programmable clock generator family targeting high-speed serial interface timing - specifically addressing PCIe, Ethernet, Fibre Channel, and broadcast video applications requiring multi-output, low-jitter, and field-reprogrammable capability.

FAQ

What is the primary function of the SI5338B-B11486-GM in a timing architecture?

The SI5338B-B11486-GM serves as a quad-output, I²C-programmable clock generator that replaces up to four discrete oscillators. It synthesizes any frequency on each of its four outputs using MultiSynth™ technology, delivering 0.7 ps RMS typical phase jitter and PCIe Gen 1–4 compliance. Its role is to provide precise, independent, low-jitter clocks to processors, FPGAs, SerDes lanes, and high-speed interfaces - all from a single 4 × 4 mm QFN package.

Does the SI5338B-B11486-GM support spread-spectrum clocking, and how is it configured?

Yes, the SI5338B-B11486-GM supports per-output spread-spectrum clocking (SSC) with user-selectable parameters: frequency range (5–350 MHz), spread magnitude (0.5–5.0%), and modulation rate (33–63 kHz). SSC is configured via I²C registers or ClockBuilder Pro software - no external components required. The feature is enabled independently on any output and maintains jitter compliance for PCIe and EMI-sensitive applications.

Can the SI5338B-B11486-GM operate without an external crystal?

Yes, the SI5338B-B11486-GM can operate without an external crystal by accepting alternative reference inputs: CMOS (5–200 MHz), SSTL/HSTL (5–350 MHz), or differential (5–710 MHz) signals on dedicated input pins. An external crystal (8–30 MHz) is optional and used only when highest stability or lowest phase noise is required. The device's internal oscillator circuitry supports all modes without hardware change.

How does the SI5338B-B11486-GM handle phase alignment between its four outputs?

The SI5338B-B11486-GM provides independent programmable phase offset on each output with ±45 ns range and <20 ps step resolution. Phase alignment is achieved via register writes over I²C or pin-controlled adjustments. Skew between outputs is minimized by shared MultiSynth™ synthesis stages and matched internal routing - measured at ≤100 ps pk-pk under identical conditions.

Is the SI5338B-B11486-GM pin-compatible with other Si5338 variants like the Si5338A or Si5338C?

Yes, all Si5338 variants - including SI5338B-B11486-GM, Si5338A-B11486-GM, and Si5338C-B11486-GM - share identical 24-QFN package, pinout, register map, and electrical interface. Differences lie solely in factory-programmed NVM content (startup configuration, default PLL settings, and jitter optimization profiles), not hardware or pin assignment.