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Home > Products > Integrated Circuits (ICs) > Clock/Timing > Application Specific Clock/Timing

Diodes Incorporated PI6C557-03AQE

Name: PI6C557-03AQE
Brand: Diodes Incorporated
SKU: PI6C557-03AQE
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: PI6C557-03AQE

Manufacturer:: Diodes Incorporated

Category:: Application Specific Clock/Timing

Package:: 16-SSOP (0.154", 3.90mm Width)

Datasheet:: PI6C557-03AQE.pdf

Description:: IC CLOCK GENERATOR 16QSOP

Quantity:: RFQ Add To RFQ list

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Product details

Overview

PI6C557-03AQE from Diodes Incorporated is a PCIe 2.0-compliant spread spectrum clock generator with two HCSL differential outputs, 3.3V supply, 25MHz crystal input, and programmable output frequencies (25/100/125/200MHz) for EMI reduction in PC and embedded host systems.

For engineers reviewing the PI6C557-03AQE datasheet, PI6C557-03AQE pinout, PI6C557-03AQE application, or PI6C557-03AQE equivalent, key selection criteria include PCIe 2.0 RMS jitter ≤3.1ps, HCSL current-mode drive (0.8V differential), spread-spectrum selection via SS0/SS1 pins, and industrial temperature support (–40°C to +85°C).

Technical Context

The PI6C557-03AQE implements a proprietary Phase-Locked Loop architecture to synthesize four precise output frequencies from a single 25MHz crystal input. It supports both HCSL and LVDS-compatible output levels via external termination configuration.

Spread spectrum modulation is selectable at –0.5%, –0.75%, or zero spread using dedicated SS0/SS1 pins, with modulation frequency fixed at 30–33kHz. Output enable (OE) provides tri-state control with 10μs enable/disable timing.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Type	HCSL differential pair (0.8V current mode); LVDS-compatible with external biasing
Input Frequency	25MHz fundamental-mode crystal or single-ended clock
Output Frequencies	25MHz, 100MHz, 125MHz, or 200MHz - selected by S0/S1 pins per Table 1
PCIe 2.0 Jitter	3.1ps RMS (typical) - meets PCIe 2.0 specification for reference clock stability
Supply Voltage	3.3V ±10% - requires dual VDDX/VDDA rails with local 0.01μF decoupling per pin
Operating Temp	–40°C to +85°C ambient - qualified for industrial-grade system deployment
Spread Options	–0.5%, –0.75%, or no spread - selected via SS0/SS1 pins; bypass option available

Pinout & Package

PI6C557-03AQE is packaged in a 16-pin QSOP (Q16), 150mil wide, lead-free and RoHS-compliant.

Pin/Terminal	Circuit Role	Design Meaning
1 S0	Frequency select input	Selects output frequency (25/100/125/200MHz) with S1; internal pull-up
2 S1	Frequency select input	MSB of 2-bit frequency code; used with S0 per Table 1
3 SS0	Spread select input	LSB of 2-bit spread code (–0.5%/–0.75%/none); internal pull-up
4 X1/CLK	Clock input	Accepts 25MHz crystal or single-ended clock; connects to X2 for crystal mode
5 X2	Crytal output	Crystal load terminal; left unconnected when using external clock input
6 OE	Output enable	Active-low; tri-states all CLK outputs when LOW; internal pull-up
7 GNDX	Crytal ground	Dedicated ground return for crystal circuit; separate from analog/digital grounds
8 SS1	Spread select input	MSB of 2-bit spread code; used with SS0 per Table 2
9 IREF	Current reference output	Sinks 2.32mA when RR = 475Ω; sets HCSL output current (IOH = 6×IREF)
10 CLK1	HCSL output (complement)	Differential complement of CLK1; requires 33Ω series + 49.9Ω termination to ground
11 CLK1	HCSL output (true)	True-side HCSL clock output; paired with Pin 10 for 100Ω differential routing
12 VDDA	Analog power supply	+3.3V rail for PLL/analog circuitry; requires dedicated 0.01μF decoupling
13 GNDA	Analog ground	Reference ground for analog/PLL section; isolated from digital ground planes
14 CLK0	HCSL output (complement)	Differential complement of CLK0; routed as 100Ω coupled microstrip/stripline
15 CLK0	HCSL output (true)	True-side HCSL clock output; paired with Pin 14 for PCIe 2.0 compliance
16 VDDX	Crytal power supply	+3.3V rail for crystal oscillator circuit; separate from VDDA/GNDA

Key Features

Feature	Design Value
PCIe 2.0 Compliance	Meets PCIe 2.0 clock jitter spec (≤3.1ps RMS) and waveform timing (tOR/tOF ≤500ps)
Programmable Spread Spectrum	Three selectable spread modes (–0.5%, –0.75%, none) via external pins - no configuration register required
HCSL Current-Mode Drive	0.8V differential swing with 6×IREF output current - eliminates need for external level-shifting
Dual Independent Outputs	Two fully independent HCSL clock pairs (CLK0/CLK1) - supports multi-lane PCIe root complex or switch designs
Industrial Temperature Range	Operates from –40°C to +85°C ambient - validated across full range for stable PLL lock and jitter performance

Applications

PCIe 2.0 Root Complex

Embedded Storage Controller

Use Scenario: Clocking a multi-lane PCIe 2.0 root complex in an industrial server motherboard.

IC Role / Device Role / Timing Role: Primary reference clock generator providing synchronized 100MHz HCSL clocks to PCIe PHY layers.

Use Value: Reduces system-level EMI by >10dB through –0.5% spread spectrum while maintaining PCIe 2.0 jitter compliance.

Use Scenario: Timing source for SATA/SAS controller ASICs in ruggedized NAS enclosures.

IC Role / Device Role / Timing Role: Low-jitter 125MHz clock generator with robust crystal interface for storage protocol timing.

Use Value: Enables reliable SATA Gen2 operation under thermal cycling due to –40°C to +85°C qualification and low phase noise.

Network Switch Fabric

Industrial GPU Compute Module

Use Scenario: Reference clock distribution for 10GbE MAC/PHY and PCIe uplink in managed Ethernet switches.

IC Role / Device Role / Timing Role: Dual-output clock source feeding both Ethernet PHY and PCIe bridge logic simultaneously.

Use Value: Eliminates need for two discrete clock ICs - reduces BOM count and layout complexity while ensuring skew <50ps between outputs.

Use Scenario: Clocking GPU memory interfaces and PCIe lanes in edge AI inference modules deployed in factory automation.

IC Role / Device Role / Timing Role: High-stability 200MHz clock generator supporting GPU memory bandwidth requirements.

Use Value: Delivers 200MHz output with <3.1ps RMS jitter - enables stable GDDR6 timing margins under variable thermal load.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
IDT8T49N242A	4-output, 3.3V LVDS-only; no HCSL support; higher integration (integrated EEPROM)	Requires external level-shifting for PCIe HCSL loads; better suited for multi-protocol systems needing LVDS flexibility	Choose when >2 outputs or programmable configuration storage are required
ICS843002AGLFT	2-output, 2.5V/3.3V dual-supply; supports PCIe 1.1 only (6ps RMS jitter)	Limited to legacy PCIe 1.1 designs; lacks spread-spectrum modulation control pins	Choose only for cost-sensitive PCIe 1.1 retrofits where spread spectrum is not mandated

Compared with IDT8T49N242A and ICS843002AGLFT, the PI6C557-03AQE uniquely combines PCIe 2.0-compliant jitter, native HCSL drive, pin-strapped spread control, and industrial temperature operation - making it optimal for new PCIe 2.0 host designs requiring minimal external components and guaranteed EMI reduction.

Availability

PI6C557-03AQE is available at Aetrix Electronics and suitable for PCIe 2.0 root complexes, embedded storage controllers, and industrial network switches requiring stable component supply, EMI-compliant clock generation, and long-term industrial temperature support.

Supply support for PI6C557-03AQE 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

Diodes Incorporated is a global semiconductor company specializing in discrete, analog, and mixed-signal ICs for power management, signal integrity, and timing applications.

The PI6C557-03AQE belongs to Diodes' PCIe-compliant clock generator product line, designed specifically to reduce electromagnetic interference in high-speed serial interconnects while meeting strict jitter and timing specifications.

FAQ

What crystal specifications are required for stable operation?

The PI6C557-03AQE requires a 25MHz fundamental-mode parallel-resonant crystal with ≤300ppm frequency tolerance over temperature and load capacitance matching the external capacitor network. Recommended parts include GC2500003 (18pF CL, ±30ppm) and FL2500047 (18pF CL, ±20ppm). Crystal capacitors must be calculated as (CL − 4) × 2 pF.

How is HCSL output current set and verified?

HCSL output current is set by the external resistor RR connected to the IREF pin: IOH = 6 × IREF. With RR = 475Ω, IREF = 2.32mA and IOH = 13.9mA - yielding the specified 0.8V differential swing into 50Ω termination. This is verified by measuring voltage across the 49.9Ω ground resistor on each CLK output leg.

Can the PI6C557-03AQE be used in LVDS mode?

Yes - the PI6C557-03AQE supports LVDS-compatible output levels using external 100Ω differential termination and 150Ω ground resistors (RP/RQ/RT), per Figure 4 in DS41266. No internal configuration is needed; only the external layout changes. LVDS mode maintains the same frequency and spread options but delivers voltage-mode (±350mV) rather than current-mode outputs.

What is the maximum allowable trace length for PCIe 2.0 HCSL routing?

For PCIe 2.0 HCSL routing, the non-coupled segments (L1/L2/L3) must be ≤0.5", ≤0.2", and ≤0.2" respectively. The coupled differential segment (L4) must be 2–16" for microstrip or 1.8–14.4" for stripline. These limits ensure signal integrity, minimize skew (<50ps), and maintain PCIe 2.0 eye diagram compliance per Figure 2 in DS41266.

PI6C557-03AQE Specifications

Product attributes: Attribute value

Manufacturer:: Diodes Incorporated

Series:: -

Package/Case:: 16-SSOP (0.154", 3.90mm Width)

Packaging:: Tube

Product Status:: Active

Programmable:: Not Verified

PLL:: Yes

Main Purpose:: Ethernet, PCI Express (PCIe)

Input:: HCSL, Crystal

Output:: HCSL, LVDS

Number of Circuits:: 1

Ratio - Input:Output:: 1:2

Differential - Input:Output:: No/Yes

Frequency - Max:: 200MHz

Voltage - Supply:: 3V ~ 3.6V

Operating Temperature:: -40°C ~ 85°C

Mounting Type:: Surface Mount

Grade:: -

Qualification:: -

Supplier Device Package:: 16-QSOP

PI6C557-03AQE FAQ

1.How can I place an order for PI6C557-03AQE through Aetrix?

Please submit a Request for Quotation (RFQ) for PI6C557-03AQE on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for PI6C557-03AQE reliable?

The price and inventory of PI6C557-03AQE are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for PI6C557-03AQE is usually 5 days.

3.What payment methods are accepted for PI6C557-03AQE?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for PI6C557-03AQE transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for PI6C557-03AQE?

PI6C557-03AQE orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your PI6C557-03AQE order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for PI6C557-03AQE?

For technical support, including PI6C557-03AQE datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your PI6C557-03AQE requirements.

6.How does Aetrix verify that PI6C557-03AQE is sourced from the original manufacturer or authorized distributors?

All PI6C557-03AQE products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that PI6C557-03AQE meets industry standards.

7.What is the process for return or replacement of PI6C557-03AQE?

All PI6C557-03AQE units undergo pre-shipment inspection (PSI). If there is an issue with PI6C557-03AQE, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The PI6C557-03AQE part is unused and in its original packaging.

Return procedure for PI6C557-03AQE:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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