Diodes Incorporated PI6LC48C51LEX

Overview

PI6LC48C51LEX from Pericom Semiconductor is a single-output LVCMOS clock generator optimized for Ethernet, SONET/SDH, and SATA/SAS reference clock generation. It accepts 17.5–21.25 MHz fundamental-mode crystals and delivers 70–170 MHz output with 0.2 ps typical RMS phase jitter at 155.52 MHz (1.875 MHz–20 MHz offset), operating from 3.3 V or 2.5 V supplies across –40°C to +85°C.

For engineers reviewing the PI6LC48C51LEX datasheet, PI6LC48C51LEX pinout, PI6LC48C51LEX application, or PI6LC48C51LEX equivalent, key selection criteria include its dual-supply compatibility, industrial temperature range, low-jitter synthesis architecture, FS-controlled frequency selection, and TSSOP-8 lead-free packaging for high-density timing subsystems.

Technical Context

The PI6LC48C51LEX integrates a PLL-based frequency synthesizer with a 32× feedback divider and programmable output dividers selected via the FS pin. Its analog power rail (VDDA) is isolated from digital supply (VDD) to minimize supply-induced jitter, and it supports both crystal and single-ended LVCMOS input modes on XTAL_IN.

It uses a fundamental-mode parallel-resonant crystal (18 pF load, 50 Ω ESR max) with external C1=33 pF and C2=22 pF load capacitors. Output duty cycle is tightly controlled at 48–52%, and rise/fall times are specified at 200–800 ps (20%–80%), ensuring clean edge integrity for high-speed serial interfaces.

Key Specifications

Pinout & Package

Package: 8-pin Pb-free Green TSSOP (173 mil width), JEDEC MO-153F/AA compliant, with exposed pad not present.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDT8T49N242A-XXLFT and Si5338A-B-GM, the PI6LC48C51LEX offers lower BOM cost, smaller TSSOP-8 footprint, and zero-configuration operation - ideal for cost-sensitive, single-output Ethernet/SONET/SATA reference clocking where fixed frequencies suffice.

Availability

PI6LC48C51LEX is available at Aetrix Electronics and suitable for Ethernet switch timing, SONET/SDH line cards, SATA/SAS host controllers, and server BMC timing requiring stable component supply across industrial temperature ranges and long production lifecycles.

Supply support for PI6LC48C51LEX 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 clock, interface, and signal-integrity solutions for communications and computing infrastructure.

The PI6LC48C51LEX belongs to the HiFlex family - designed specifically for low-jitter, single-output clock generation in wired connectivity applications including Gigabit Ethernet, SONET/SDH, and Serial ATA.

FAQ

What crystal specifications are mandatory for stable PI6LC48C51LEX operation?

The device requires a fundamental-mode, parallel-resonant crystal with 17.5–21.25 MHz frequency, 18 pF load capacitance, ≤50 Ω ESR, and ≤1 mW drive level. Pericom recommends FLxxxx (3.2×2.5 mm) or FYxxxxx (5×3.2 mm) series crystals with ±20 ppm or ±30 ppm tolerance. Deviations outside these specs risk startup failure or increased jitter.

Can PI6LC48C51LEX accept an external LVCMOS clock instead of a crystal?

Yes - the XTAL_IN pin accepts AC-coupled single-ended LVCMOS signals with edge rates up to 10 ns. XTAL_OUT must be left floating in this mode. Amplitude should be reduced to half-swing to avoid power rail interference, and the driver's output impedance plus series resistor must match the transmission line (typically 50 Ω).

How does the FS pin affect output frequency selection?

The FS pin selects between two pre-defined output frequencies for each crystal frequency. When FS = low, output = crystal × N₁; when FS = high, output = crystal × N₂. For example, with a 19.44 MHz crystal: FS = 0 → 155.52 MHz, FS = 1 → 77.76 MHz. No external programming or EEPROM is involved - selection is hardwired.

Why are separate VDD and VDDA supplies required, and how should they be decoupled?

VDD powers digital logic and output drivers; VDDA powers the analog PLL and VCO. Separation prevents digital switching noise from modulating the VCO. VDD requires a 0.1 µF ceramic capacitor; VDDA requires a 10 µF bulk capacitor in series with a 10 Ω resistor (for 3.3 V) to form a low-pass filter that attenuates >100 kHz noise.