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

Diodes Incorporated PI6C557-03AQLE

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

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Part No.:: PI6C557-03AQLE

Manufacturer:: Diodes Incorporated

Category:: Application Specific Clock/Timing

Package:: 16-TSSOP (0.173", 4.40mm Width)

Datasheet:: PI6C557-03AQLE.pdf

Description:: IC CLOCK GENERATOR 16TSSOP

Quantity:: RFQ Add To RFQ list

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Product details

Overview

PI6C557-03AQ from Diodes Incorporated is a PCIe 2.0-compliant spread spectrum clock generator for automotive-grade embedded systems, accepting a 25MHz crystal input and delivering two HCSL differential clock outputs at 25/100/125/200MHz with selectable -0.5% or -0.75% down-spread to reduce EMI in PC and server motherboard timing paths.

For engineers reviewing the PI6C557-03AQ datasheet, PI6C557-03AQ pinout, PI6C557-03AQ application, or PI6C557-03AQ equivalent, this device supports precise PCIe 2.0 clocking with RMS phase jitter ≤3.1ps, cycle-to-cycle jitter ≤60ps, and AEC-Q100 qualification for under-hood automotive electronics design.

Technical Context

This device implements a proprietary PLL architecture that locks to a 25MHz fundamental-mode crystal and synthesizes four discrete output frequencies via S1/S0 control pins. Spread spectrum modulation is applied digitally using a 30–33kHz triangular waveform generator with programmable depth (-0.5%, -0.75%, or off) selected by SS1/SS0.

All outputs are current-mode HCSL drivers (0.8V common-mode, 6×IREF output current), configured for 100Ω differential termination. OE pin enables tri-state control of both CLK0 and CLK1 output pairs, while IREF sets internal current reference via external 475Ω resistor for 50Ω trace impedance matching.

Key Specifications

Parameter	Value and Actual Design Meaning
Input Frequency	25MHz crystal or single-ended clock - fixed reference for all synthesized outputs
Output Frequencies	25MHz, 100MHz, 125MHz, 200MHz - selected via S1/S0 logic pins per Table 1
RMS Phase Jitter	≤3.1ps @100MHz - meets PCIe 2.0 specification for reference clock stability
Cycle-to-Cycle Jitter	≤60ps (typ. 35ps) - ensures timing margin for high-speed serial link receivers
Spread Spectrum Depth	-0.5% or -0.75% down-spread - reduces peak EMI amplitude without affecting system timing budget
Supply Voltage	3.3V ±10% - requires dual VDDA/VDDX rails and separate GNDA/GNDX grounds for analog/digital isolation
Operating Temperature	-40°C to +85°C - qualified per AEC-Q100 Grade 3 for automotive under-dash applications

Pinout & Package

Package: 16-pin TSSOP (L), 173mil wide, Pb-free and RoHS 3 compliant, thermal resistance θJA = 90°C/W.

Pin/Terminal	Circuit Role	Design Meaning
1 S0	Frequency select input	LSB of 2-bit output frequency selection (Table 1); internal pull-up
2 S1	Frequency select input	MSB of 2-bit output frequency selection (Table 1); internal pull-up
3 SS0	Spread select input	LSB of 2-bit spread depth selection (Table 2); internal pull-up
4 X1/CLK	Clock input	25MHz crystal or single-ended clock source; connects to crystal X1 or external driver
5 X2	Clock output	Crystal X2 connection; left unconnected when using external clock input
6 OE	Output enable	Active-low tri-state control for both CLK0 and CLK1 differential pairs; internal pull-up
7 GNDX	Crytal ground	Dedicated ground return for crystal oscillator circuit; isolated from GNDA
8 SS1	Spread select input	MSB of 2-bit spread depth selection (Table 2); internal pull-up
9 IREF	Current reference output	Connects to 475Ω resistor to set 2.32mA reference; determines HCSL output drive strength
10 CLK1	HCSL clock output	True leg of second differential pair; requires 100Ω differential termination
11 CLK1	HCSL complement output	Complement leg of second differential pair; routed as matched-length pair with CLK1
12 VDDA	Analog power supply	+3.3V supply for PLL and crystal oscillator; decoupled with 0.01μF capacitor
13 GNDA	Analog ground	Ground return for analog circuits; separated from digital and crystal grounds
14 CLK0	HCSL clock output	True leg of first differential pair; used for primary PCIe reference clock path
15 CLK0	HCSL complement output	Complement leg of first differential pair; routed with controlled 100Ω differential impedance
16 VDDX	Crytal power supply	+3.3V supply dedicated to crystal oscillator circuit; decoupled separately

Key Features

Feature	Design Value
AEC-Q100 Grade 3 qualification	Validated for automotive ambient temperatures (-40°C to +85°C) and PPAP-capable manufacturing
PCIe 2.0-compliant jitter performance	RMS phase jitter ≤3.1ps and cycle-to-cycle jitter ≤60ps meet Gen2 reference clock requirements
HCSL current-mode output structure	0.8V common-mode voltage with 6×IREF drive enables robust 100Ω differential signaling into PCIe loads
Hardware-configurable spread and frequency	No firmware or I²C required - all settings controlled via 4 external logic pins (S1/S0/SS1/SS0)
Dual isolated power domains	Separate VDDA/GNDA (analog) and VDDX/GNDX (crystal) supplies minimize noise coupling into PLL

Applications

Automotive Infotainment Head Unit

Server Motherboard PCIe Clock Distribution

Use Scenario: Timing reference for multiple PCIe 2.0 peripherals (GPU, NVMe, NIC) in a vehicle head unit with strict EMI limits.

IC Role / Device Role / Timing Role: Primary spread spectrum clock generator providing two independent HCSL clock trees synchronized to a single 25MHz crystal.

Use Value: -0.75% down-spread reduces radiated emissions by >10dB at 100MHz harmonics, enabling compliance with CISPR 25 Class 5.

Use Scenario: Central clock source for multi-slot server motherboard supporting up to four PCIe 2.0 x16 slots.

IC Role / Device Role / Timing Role: Low-jitter clock fanout device generating matched 100MHz HCSL clocks for slot-level reference distribution.

Use Value: 50ps inter-output skew ensures simultaneous clock arrival across slots, preserving PCIe timing margins under thermal drift.

Industrial Edge AI Accelerator Card

Automotive ADAS Camera Hub Controller

Use Scenario: Reference clock for FPGA-based vision processing card with PCIe host interface and MIPI CSI-2 camera inputs.

IC Role / Device Role / Timing Role: Dual-output clock generator supplying 100MHz PCIe clock and 200MHz pixel clock derived from same PLL.

Use Value: Single-crystal architecture eliminates clock domain crossing issues between PCIe and image sensor subsystems.

Use Scenario: Timing engine for multi-camera fusion controller aggregating data from four 12MP automotive cameras over MIPI.

IC Role / Device Role / Timing Role: AEC-Q100-qualified clock source delivering 125MHz HCSL clock to image signal processor and 25MHz to microcontroller.

Use Value: Guaranteed operation at +85°C ambient enables placement near heat-generating SoCs without derating.

Equivalent & Alternatives

The following parts are listed as comparable options for similar PCIe 2.0 spread spectrum clock generator applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
ICS8430M-01T	LVDS-only outputs; no HCSL support; higher RMS jitter (4.5ps)	Lacks AEC-Q100 qualification; not suitable for automotive under-hood use	Select when LVDS interface compatibility is mandatory and automotive qualification is unnecessary
PI6C20400WEX	Four LVDS outputs; wider frequency range (12–200MHz); no spread spectrum	Designed for general-purpose clock fanout, not EMI-sensitive PCIe 2.0 systems	Select when multi-output fanout is needed without spread spectrum, and PCIe compliance is secondary

Compared with ICS8430M-01T and PI6C20400WEX, the PI6C557-03AQ uniquely combines AEC-Q100 qualification, HCSL output drive, and hardware-selectable spread spectrum-making it the only option for automotive PCIe 2.0 timing where EMI reduction and temperature robustness are co-required.

Availability

PI6C557-03AQ is available at Aetrix Electronics and suitable for automotive infotainment systems, server motherboard designs, and industrial edge AI accelerator cards requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for PI6C557-03AQ 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 manufacturer of discrete semiconductors and integrated circuits, specializing in high-performance timing, power management, and signal integrity solutions for automotive, industrial, and computing markets.

The PI6C557-03AQ belongs to Diodes' Pericom timing product line, engineered specifically for low-jitter, spread-spectrum clock generation in PCIe 2.0 and automotive Ethernet applications where EMI suppression and AEC-Q100 reliability are mandatory.

FAQ

What crystal specifications are required for stable operation?

The PI6C557-03AQ requires a 25MHz fundamental-mode parallel-resonant crystal with load capacitance of 20pF, frequency tolerance ±15ppm, and stability ±20ppm over temperature. Diodes recommends part FL2500184Q; external capacitors C1/C2 should each be 27pF for CL=20pF crystals, with optional 360Ω series resistor for drive-level control.

How is HCSL output termination implemented on the PCB?

HCSL outputs require 100Ω differential termination: each CLKx/CLKx pair must be routed as a controlled 100Ω differential microstrip or stripline, with series resistors (RS = 33Ω) placed near the PI6C557-03AQ and parallel termination (RT = 49.9Ω) at the receiver end per PCI Express Layout Guidelines. No AC coupling capacitors are needed.

Can the device operate in LVDS mode?

Yes - the PI6C557-03AQ supports LVDS-compatible voltage levels by configuring external termination: use 100Ω differential termination (RP/RQ = 100Ω) and 150Ω pull-down (RT = 150Ω) per LVDS layout guidelines. Output common-mode voltage shifts to ~1.2V, meeting LVDS electrical standards while retaining the same PLL and spread functionality.

What is the function of the IREF pin and how is it used?

IREF is an output pin that sources a precision 2.32mA current when a 475Ω resistor is connected to ground. This current sets the HCSL output drive strength (IOH = 6 × IREF ≈ 13.9mA), ensuring correct 50Ω single-ended impedance matching for 100Ω differential traces. The resistor must be placed close to the IREF pin with minimal trace length.

PI6C557-03AQLE Specifications

Product attributes: Attribute value

Manufacturer:: Diodes Incorporated

Series:: -

Package/Case:: 16-TSSOP (0.173", 4.40mm Width)

Packaging:: Tube

Product Status:: Active

Programmable:: Not Verified

PLL:: Yes

Main Purpose:: Ethernet, PCI Express (PCIe)

Input:: Clock, 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:: Automotive

Qualification:: AEC-Q100

Supplier Device Package:: 16-TSSOP

PI6C557-03AQLE FAQ

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

Please submit a Request for Quotation (RFQ) for PI6C557-03AQLE 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 PI6C557-03AQLE reliable?

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

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

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

Note: Certain payment methods may incur a processing fee.

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

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

Once your PI6C557-03AQLE 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 PI6C557-03AQLE?

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

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

All PI6C557-03AQLE 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 PI6C557-03AQLE meets industry standards.

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

All PI6C557-03AQLE units undergo pre-shipment inspection (PSI). If there is an issue with PI6C557-03AQLE, 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 PI6C557-03AQLE part is unused and in its original packaging.

Return procedure for PI6C557-03AQLE:

1.Submit a request within 90 days.

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

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