Skyworks Solutions Inc. SI5338A-B01449-GMR

Overview

SI5338A-B01449-GMR 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 Common Clock and Gen 3 SRNS compliance, and operation across –40 to +85 °C. It replaces up to four crystal oscillators in Ethernet switch/router, PCIe, and FPGA clocking systems.

For engineers reviewing the SI5338A-B01449-GMR datasheet, SI5338A-B01449-GMR pinout, SI5338A-B01449-GMR application, or SI5338A-B01449-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 24-pin 4×4 mm QFN package with I²C/SMBus programming interface.

Technical Context

The SI5338A-B01449-GMR implements a two-stage PLL architecture: a high-stability reference stage (with crystal or external clock input) feeding a fractional-N MultiSynth™ synthesis stage per output. Each of the four outputs features independent frequency, format (LVPECL/LVDS/HCSL/CMOS/SSTL/HSTL), voltage, phase offset (±45 ns), and spread-spectrum control.

It supports flexible reference inputs - 8–30 MHz crystal, 5–200 MHz CMOS, 5–350 MHz SSTL/HSTL, or 5–710 MHz differential - and enables glitchless frequency adjustment in 1 ppm steps via dedicated pins or I²C. Loss-of-lock and loss-of-signal alarms provide real-time status monitoring for system reliability.

Key Specifications

Pinout & Package

SI5338A-B01449-GMR uses a 24-pin, 4 × 4 mm QFN package with exposed thermal pad. Pin 1 is top-left (IN1), pin 24 is bottom-right (GND). The package supports reflow soldering per JEDEC J-STD-020 (peak 260 °C).

Key Features

Applications

Equivalent & Alternatives

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

Compared with Si5338A-B01450-GMR, SI5338A-B01449-GMR provides identical performance but with a distinct factory-programmed configuration; versus LMK04832RHAT, it delivers 40% lower power, 50% smaller footprint, and finer-grained per-output spread-spectrum control - critical for space-constrained PCIe and Ethernet designs.

Availability

SI5338A-B01449-GMR is available at Aetrix Electronics and suitable for Ethernet switch/router timing, PCIe Gen 1–4 clock distribution, and FPGA/processor clocking applications requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for SI5338A-B01449-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 leader in analog and mixed-signal semiconductors, specializing in RF, mobile, infrastructure, and timing solutions with over 30 years of RF and clock innovation.

The Si5338 family is designed for high-performance, low-jitter clock generation in data center, telecom, and broadcast systems - enabling consolidation of multiple oscillators into a single programmable IC with zero-ppm synthesis accuracy.

FAQ

What is the primary function of the SI5338A-B01449-GMR in a system design?

The SI5338A-B01449-GMR serves as an I²C-programmable quad clock generator that synthesizes up to four independent, any-frequency output clocks (0.16–710 MHz) from a single reference input. It replaces multiple discrete oscillators in systems like PCIe root complexes and Ethernet switches, delivering 0.7 ps RMS jitter and PCIe Gen 4 compliance while reducing board space and BOM count. Its MultiSynth™ architecture ensures true zero-ppm frequency accuracy on all outputs.

Does the SI5338A-B01449-GMR support spread-spectrum clocking, and how is it configured?

Yes, the SI5338A-B01449-GMR supports per-output spread-spectrum clocking (SSC) with programmable deviation (0.5–5.0% down-spread) and modulation rate (33–63 kHz). SSC is configured independently for each output via I²C registers or ClockBuilder Pro software. Hardware pin control is not available for SSC; it must be enabled and tuned through the serial interface. This feature helps reduce EMI in dense PCB layouts without affecting timing integrity.

Can the SI5338A-B01449-GMR operate with a 25 MHz crystal input, and what load capacitance is required?

Yes, the SI5338A-B01449-GMR supports 25 MHz crystal input within its 8–30 MHz crystal frequency range. For a 25 MHz crystal, the device supports on-chip load capacitance of 11–13 pF (recommended external load: 17–19 pF), with max drive level ≤100 µW and ESR ≤75 Ω. Crystal specifications are validated per Tables 8–11 in the datasheet; AN360 provides guidance for register tuning if using non-standard CL values.

How does the SI5338A-B01449-GMR handle loss-of-signal (LOS) and loss-of-lock (LOL) detection?

The SI5338A-B01449-GMR integrates dedicated LOS and LOL detection circuits with configurable thresholds. LOS detection triggers within 2.6–5 µs of input clock disappearance; LOL detection responds within 5–10 ms after PLL unlock. Both events assert the open-drain INTR pin low. Status is also readable via I²C register bits (0x000C[7:6]), enabling firmware-driven fault recovery or system-level alarm logging without external supervision circuitry.

Is the SI5338A-B01449-GMR pin-compatible with other Si5338 variants such as the SI5338A-B01450-GMR?

Yes, the SI5338A-B01449-GMR is fully pin-compatible and functionally identical to other Si5338A-GMR variants including SI5338A-B01450-GMR. All share the same 24-pin QFN package, pin assignments, electrical characteristics, and register map. Differences exist only in factory-programmed NVM contents (e.g., default frequency configuration or reference selection), which can be overwritten via I²C. No PCB layout change is required when substituting between these variants.