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Diodes Incorporated PI6C557-05LEX
- Part No.:
- PI6C557-05LEX
- Manufacturer:
- Diodes Incorporated
- Category:
- Application Specific Clock/Timing
- Package:
- 20-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
PI6C557-05LEX.pdf
- Description:
- IC CLOCK GENERATOR TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:11,983
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Product details
Overview
PI6C557-05LEX from Diodes Incorporated is a PCIe® 2.0-compliant spread spectrum clock generator with four HCSL differential outputs, 3.3V supply, 25MHz crystal input, and selectable -0.5%/-1.0%/-1.5% or no spread. It delivers 100/200MHz outputs with 2.1ps RMS phase jitter (typ) and operates across -40°C to +85°C for EMI reduction in PC and embedded host systems.
For engineers reviewing the PI6C557-05LEX datasheet, PI6C557-05LEX pinout, PI6C557-05LEX application, or PI6C557-05LEX equivalent, key selection criteria include PCIe 2.0 timing compliance, HCSL/LVDS output compatibility, spread-spectrum configuration via S[2:0] pins, and industrial temperature operation with 20-pin TSSOP packaging.
Technical Context
The PI6C557-05LEX employs a proprietary PLL architecture to synthesize 100MHz or 200MHz differential clocks from a 25MHz fundamental-mode crystal or CMOS reference. Spread spectrum modulation is digitally controlled via three external pins (S2–S0), enabling eight discrete configurations including no-spread mode.
It supports dual-output termination schemes: HCSL (0.7V current-mode, 33Ω series + 49.9Ω ground) and LVDS-compatible (100Ω differential, 150Ω termination). Output enable (OE) and power-down (PD) pins provide dynamic control with internal pull-ups, and IREF sets output current at 2.32mA (RR = 475Ω) for precise 6×IREF drive strength.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Frequency | 100MHz or 200MHz - selectable per spread table; matches PCIe Gen2 reference clock requirements. |
| Phase Jitter (RMS) | 2.1ps (typ) - meets PCI-SIG jitter test method for Gen2 compliance at 100/200MHz. |
| Supply Voltage | 3.3V ±5% - requires decoupling capacitors (0.01μF/0.1μF) at each VDD pin for noise isolation. |
| Cycle-to-Cycle Jitter | 40ps (typ) - ensures stable edge placement across consecutive cycles for timing-critical interfaces. |
| Spread Spectrum Options | -0.5%, -1.0%, -1.5%, or no spread - configured via S2/S1/S0 pins; modulates at 30–33kHz. |
| Operating Temperature | -40°C to +85°C - qualified for industrial-grade embedded and computing platforms. |
| Output Type | HCSL (0.7V current-mode) or LVDS-compatible - configurable via PCB layout; not internally switchable. |
Pinout & Package
Package: 20-pin TSSOP (173mil wide), Pb-free and RoHS-compliant (suffix "E"), tape-and-reel (suffix "X").
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VDDXD (Pin 1) | Digital power supply | +3.3V digital rail; requires local 0.01μF/0.1μF decoupling to GND. |
| S0–S2 (Pins 2–4) | Spread/frequency select inputs | Three-bit code selects spread % and output frequency (100/200MHz); internal pull-up resistors. |
| X1/CLK (Pin 5) | Clock reference input | Accepts 25MHz crystal (parallel resonant, ≤30ppm) or 25MHz CMOS clock; X2 left open for external clock mode. |
| PD (Pin 7) | Power-down control | Active-low; places device in low-current state (<100µA) when pulled low; internal pull-up. |
| OE (Pin 8) | Output enable | Active-high; enables/disables all CLKx outputs with 10µs enable/disable timing; internal pull-up. |
| IREF (Pin 10) | Current reference output | Drives external 475Ω resistor to set 2.32mA reference; determines 6×IREF output drive strength. |
| CLK0–CLK3 (Pins 11–20) | Differential clock outputs | Four true/complement pairs (CLK0–CLK3); HCSL or LVDS layout-dependent; require external termination. |
Key Features
| Feature | Design Value |
|---|---|
| PCIe® 2.0 compliance | Validated against PCI-SIG jitter, skew (≤50ps), and waveform specifications for host-side clock generation. |
| Configurable spread spectrum | Eight discrete modes via S[2:0], including no-spread, enabling EMI reduction without firmware or register writes. |
| HCSL/LVDS layout flexibility | No internal mode switching - output electrical behavior determined solely by PCB routing and termination. |
| Industrial temperature range | Guaranteed operation from -40°C to +85°C with full AC/DC specs maintained across range. |
| Low-power control interface | OE and PD pins use internal pull-ups, eliminating need for external biasing in most system designs. |
Applications
| Desktop Motherboard Clocking | Embedded Computing Platform |
|---|---|
Use Scenario: Generating synchronized 100MHz PCIe reference clocks for multiple slots and chipsets on ATX motherboards. IC Role / Device Role / Timing Role: Primary spread spectrum clock generator providing four HCSL differential pairs to reduce broadband EMI emissions. Use Value: Meets FCC Class B radiated emission limits without added shielding or ferrites, lowering BOM cost and board area. | Use Scenario: Providing timing for multi-function industrial controllers with PCIe-based expansion modules and onboard peripherals. IC Role / Device Role / Timing Role: Central clock source for CPU, GPU, and peripheral bridges operating in harsh thermal environments. Use Value: Maintains <2.1ps RMS jitter across -40°C to +85°C, ensuring reliable link training and data integrity under thermal stress. |
| Network Interface Card (NIC) | Storage Controller Board |
Use Scenario: Driving high-speed serial links in 10GbE NICs requiring low-jitter, spread-spectrum clocking for PCIe Gen2 x4 lanes. IC Role / Device Role / Timing Role: PCIe 2.0-compliant clock synthesizer delivering 200MHz outputs with <40ps cycle-to-cycle jitter. Use Value: Enables deterministic latency and error-free packet transmission at line rate by meeting PCIe timing margin requirements. | Use Scenario: Clocking SAS/SATA host bus adapters and NVMe controller boards where EMI must be minimized near sensitive analog circuitry. IC Role / Device Role / Timing Role: Spread spectrum clock generator with configurable spread to suppress narrowband EMI peaks near storage PHY frequencies. Use Value: Reduces peak radiated emissions by >10dB at 100MHz harmonics, easing EMC certification for enterprise storage systems. |
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 | LVDS-only outputs; integrated crystal oscillator; programmable via I²C; higher RMS jitter (3.5ps). | Requires I²C host control and lacks HCSL support; better suited for systems needing flexible frequency synthesis. | Select when firmware-controlled frequency agility or integrated XO is required over fixed 100/200MHz HCSL outputs. |
| ICS843002AG-01 | Four LVPECL outputs; 3.3V supply; 2.5ps RMS jitter; no spread spectrum; fixed 100MHz only. | Higher power consumption; no EMI reduction capability; incompatible with HCSL receivers. | Choose only if absolute lowest jitter is prioritized and EMI mitigation is handled elsewhere in the design. |
Compared with IDT8T49N242A and ICS843002AG-01, the PI6C557-05LEX uniquely combines PCIe 2.0-compliant HCSL outputs, hardware-configurable spread spectrum, and industrial temperature operation without requiring serial programming or external oscillators-making it optimal for cost-sensitive, high-volume PC and embedded host designs.
Availability
PI6C557-05LEX is available at Aetrix Electronics and suitable for desktop motherboard clocking, embedded computing platforms, and network interface card designs requiring stable component supply, EMI-compliant timing, and industrial temperature resilience.
Supply support for PI6C557-05LEX 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, energy-efficient solutions for computing, industrial, and communications markets.
The PI6C557-05LEX belongs to Diodes' PCIe clock generator product line, engineered specifically to meet PCI-SIG Gen2 timing and EMI requirements in space-constrained, thermally demanding host systems.
FAQ
What crystal specifications are required for stable operation?
The PI6C557-05LEX requires a 25MHz fundamental-mode parallel-resonant crystal with load capacitance of 18pF and frequency tolerance ≤±30ppm across -40°C to +85°C. Recommended part numbers include GC2500003, FY2500081, and FL2500047 - all validated for low-phase-noise performance and reliable startup.
Can the device operate with an external 25MHz clock instead of a crystal?
Yes - the X1/CLK pin accepts a 25MHz CMOS clock signal directly. When using an external clock, leave X2 unconnected (open). For non-3.3V XO sources (e.g., 2.5V or 1.8V), AC coupling with optional DC Thevenin termination is required to maintain logic thresholds and minimize jitter degradation.
How is HCSL vs. LVDS output behavior determined?
HCSL or LVDS electrical behavior is defined entirely by PCB layout and termination - not internal configuration. HCSL uses 33Ω series + 49.9Ω ground termination; LVDS uses 100Ω differential + 150Ω termination. No register or pin setting changes the driver's intrinsic current-source nature.
What is the function of the IREF pin and how is it used?
IREF outputs a precision 2.32mA current when a 475Ω resistor is connected to ground. This sets the internal current reference for all four HCSL output drivers, ensuring consistent 0.7V common-mode voltage and matched drive strength across all CLKx pairs - critical for skew control and signal integrity.
PI6C557-05LEX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Series:
- -
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- 1:4
- Differential - Input:Output:
- No/Yes
- Frequency - Max:
- 200MHz
- Voltage - Supply:
- 3.135V ~ 3.465V
- Operating Temperature:
- -40°C ~ 85°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 20-TSSOP
PI6C557-05LEX FAQ
1.How can I place an order for PI6C557-05LEX through Aetrix?
Please submit a Request for Quotation (RFQ) for PI6C557-05LEX 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 PI6C557-05LEX reliable?
The price and inventory of PI6C557-05LEX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for PI6C557-05LEX is usually 5 days.
3.What payment methods are accepted for PI6C557-05LEX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for PI6C557-05LEX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for PI6C557-05LEX?
PI6C557-05LEX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your PI6C557-05LEX 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 PI6C557-05LEX?
For technical support, including PI6C557-05LEX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your PI6C557-05LEX requirements.
6.How does Aetrix verify that PI6C557-05LEX is sourced from the original manufacturer or authorized distributors?
All PI6C557-05LEX 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 PI6C557-05LEX meets industry standards.
7.What is the process for return or replacement of PI6C557-05LEX?
All PI6C557-05LEX units undergo pre-shipment inspection (PSI). If there is an issue with PI6C557-05LEX, 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 PI6C557-05LEX part is unused and in its original packaging.
Return procedure for PI6C557-05LEX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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