Diodes Incorporated PI6LC4820ZDEX

Overview

PI6LC4820ZDEX from Pericom Semiconductor is a low-phase-noise LC-VCO-based clock generator designed for 10GbE and multi-rate Ethernet systems. It accepts 25 MHz crystal or 25/156.25 MHz differential inputs, delivers up to nine LVPECL/LVDS outputs at 312.5/156.25/125 MHz, and achieves ≤1 ps integrated phase jitter (12 kHz–20 MHz) with 3.3 V supply.

For engineers reviewing the PI6LC4820ZDEX datasheet, PI6LC4820ZDEX pinout, PI6LC4820ZDEX application, or PI6LC4820ZDEX equivalent, key selection criteria include bank-selectable output formats, PLL bypass mode for test, input mux flexibility (crystal/diff/SE), power supply noise rejection (–50 dBc @ 156.25 MHz), and TQFN-48 thermal performance in high-density switch/router timing designs.

Technical Context

The PI6LC4820ZDEX implements an LC-based VCO with programmable feedback dividers (FS1 selects ÷20 or ÷25) and three independent output banks (A/B/C), each configurable via dedicated FS and mode pins. Its input multiplexer supports crystal (X1/X2), differential (IN+/IN−), or single-ended (IN_SE) sources, with IN_SEL selecting between them.

Each bank features per-output voltage-domain control (VDD_QA/VDD_QB/VDD_QC), selectable LVPECL/LVDS drive strength via QA_Mode0/QA_Mode1/QB_Mode/QC_Mode, and independent frequency division (FS_A/FS_B/FS_C select 125/156.25/312.5 MHz). PLL bypass mode routes input directly to outputs while preserving bank-specific formatting.

Key Specifications

Pinout & Package

PI6LC4820ZDEX is housed in a 48-lead, 7×7 mm, 0.5 mm pitch Pb-free TQFN package (ZD48) with exposed thermal pad. Pin numbering follows standard counter-clockwise layout starting from top-left corner (Pin 1 = FS0).

Key Features

Applications

Equivalent & Alternatives

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

Compared with Si5332A-D-GM and ICS843002AGI-01LFT, the PI6LC4820ZDEX uniquely balances fixed Ethernet rate optimization, on-chip crystal buffering, and bank-level configurability-making it ideal for space-constrained, multi-port 10GbE systems requiring deterministic jitter performance without firmware overhead.

Availability

PI6LC4820ZDEX is available at Aetrix Electronics and suitable for 10GbE line cards, multi-rate Ethernet switches, optical transport modules, and network processor timing applications requiring stable component supply, full traceability, and long-term lifecycle support.

Supply support for PI6LC4820ZDEX 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

Pericom Semiconductor (acquired by Diodes Incorporated in 2016) specialized in high-performance timing, signal integrity, and interface solutions for networking and communications infrastructure.

The PI6LC4820 belongs to Pericom's HiFlex™ Ethernet clock generator family, engineered specifically for low-jitter, multi-rate timing in 10GbE and emerging 25G/50G switch fabric applications with emphasis on ease of layout and noise immunity.

FAQ

What crystal specifications are required for reliable operation?

The PI6LC4820ZDEX requires a fundamental-mode 25 MHz crystal with 18 pF load capacitance, ≤50 Ω ESR, and ±30 ppm stability. Recommended parts include SaRonix-eCera GC25000-76B and Pericom FL2500047. External load capacitors C1=27 pF and C2=33 pF are specified for CL=18 pF crystals; values may be tuned for board parasitics.

How does PLL bypass mode affect output jitter and timing path?

In PLL bypass mode (PLL_BYPS = 1), the input reference passes directly to outputs without VCO or divider stages, reducing propagation delay and eliminating PLL-induced jitter. Output jitter reverts to the source's intrinsic phase noise-e.g., ~0.3 ps RMS for a high-quality 25 MHz crystal-making it ideal for lab validation and deterministic timing analysis.

Can all nine outputs operate at different frequencies simultaneously?

No. Outputs are grouped into three banks (A/B/C), each constrained to a single frequency selected by FS_A/FS_B/FS_C. Bank A supports five outputs at one frequency, Bank B three outputs at another, and Bank C one differential pair at a third-enabling up to three distinct simultaneous frequencies (e.g., 312.5/156.25/125 MHz) across the device.

What is the purpose of the X2 pin beyond crystal oscillation?

X2 provides a buffered, low-noise copy of the crystal oscillator signal-distinct from PLL-derived outputs. It serves as a clean 25 MHz reference for external components like PHYs, SerDes PLLs, or monitoring circuits, avoiding injection of PLL phase noise or supply ripple present on VDD_Qx-rail outputs.