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

NXP Semiconductors MPC940LFAR2

Name: MPC940LFAR2
Brand: NXP Semiconductors
SKU: MPC940LFAR2
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MPC940LFAR2

Manufacturer:: NXP Semiconductors

Category:: Application Specific Clock/Timing

Package:: 32-LQFP

Datasheet:: MPC940LFAR2.pdf

Description:: IC CLOCK DISTRIBUTON 1:18 32LQFP

Quantity:: RFQ Add To RFQ list

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Product details

Overview

MPC940LFAR2 from Freescale Semiconductor is a 1:18 low-voltage clock distribution IC with dual-supply flexibility (2.5V/3.3V core and output rails), LVPECL or LVCMOS selectable input, 18 LVCMOS outputs, and 150 ps max output-to-output skew - designed for high-performance microprocessor clock trees including Pentium II systems.

For engineers reviewing the MPC940LFAR2 datasheet, MPC940LFAR2 pinout, MPC940LFAR2 application, or MPC940LFAR2 equivalent, key selection criteria include input interface flexibility (LVPECL/LVCMOS), output drive strength for 50Ω series-terminated lines, 250 MHz max frequency support, and LQFP-32 package compatibility with tight skew requirements in synchronous digital systems.

Technical Context

The MPC940LFAR2 integrates a dual-input clock selector (LVPECL or LVCMOS) with independent VCCI/VCCO supply domains, enabling mixed-voltage system integration. Its output buffers feature ≈20–23 Ω low-impedance drive in both logic states, supporting two series-terminated 50Ω lines per output (effective fanout 1:36).

Skew control is achieved via matched internal delay paths: output-to-output skew is guaranteed ≤150 ps under 3.3V/3.3V or 3.3V/2.5V operation, and ≤200 ps under 2.5V/2.5V operation. Input selection is controlled by LVCMOS_CLK_Sel (active-HIGH), with all inputs internally pulled up/down for open-pin tolerance.

Key Specifications

Parameter	Value and Actual Design Meaning
Input Interface	Selectable LVPECL or LVCMOS clock input via LVCMOS_CLK_Sel pin; supports direct connection to MC100EP111 fanout buffers or standard CMOS clocks.
Output Count & Type	18 LVCMOS outputs (Q0–Q17); compatible with 2.5V or 3.3V I/O standards and capable of driving 50Ω series-terminated transmission lines.
Max Output Skew	150 ps (output-to-output) at VCCI = 3.3V / VCCO = 3.3V or 2.5V; ensures timing integrity across multi-processor or FPGA clock domains.
Max Input Frequency	250 MHz (with VCCI = 3.3V / VCCO = 3.3V or 2.5V); supports high-speed CPU and memory interface clocking.
Supply Flexibility	Dual-supply operation: VCCI (core) and VCCO (output) independently configurable as 2.5V ±5% or 3.3V ±5%.
Output Impedance	18–28 Ω (typical 23 Ω); enables robust signal integrity on PCB traces without external series termination resistors.
Package	32-lead LQFP (7×7 mm body, 0.8 mm pitch, Case 873A–02); optimized for thermal performance and board space in dense timing layouts.

Pinout & Package

32-lead LQFP (FA suffix, Case 873A–02), 7×7 mm body, 0.8 mm lead pitch, exposed pad not specified. Pinout validated per Freescale DL207 Rev 0 datasheet.

Pin/Terminal	Circuit Role	Design Meaning
PECL_CLK	LVPECL differential clock input	Accepts AC-coupled LVPECL signals (500–1000 mVpp, common-mode 1.9–2.7 V @ 3.3V supply); connects directly to high-frequency clock sources or fanout buffers.
LVCMOS_CLK	LVCMOS single-ended clock input	Standard CMOS-level reference clock (VIH ≥ 2.4 V @ 3.3V, ≥ 2.0 V @ 2.5V); used when LVPECL infrastructure is unavailable.
LVCMOS_CLK_Sel	Input select control	Active-HIGH logic signal; selects LVCMOS_CLK when HIGH, PECL_CLK when LOW; internal pull-down enables default PECL mode if left unconnected.
Q0–Q17	LVCMOS clock outputs	18 identical buffered outputs; each drives one or two 50Ω series-terminated lines; output voltage levels comply with 2.5V or 3.3V LVCMOS specs.
VCCI	Core supply voltage	Supplies internal logic and input receivers; must be 2.5V or 3.3V ±5%; decoupling required near pin.
VCCO	Output supply voltage	Supplies output drivers; independently set to 2.5V or 3.3V ±5%; determines VOH/VOL levels and drive strength.
GNDO	Output ground	Analog/digital ground return for output drivers; separate from GNDI to minimize noise coupling between core and output stages.
GNDI	Core ground	Ground return for internal logic and input receivers; requires dedicated low-impedance path to system ground plane.

Key Features

Feature	Design Value
Configurable dual-supply architecture	VCCI and VCCO independently set to 2.5V or 3.3V, enabling seamless integration into mixed-voltage SoC or processor platforms.
Sub-200 ps output skew guarantee	150 ps max output-to-output skew ensures deterministic timing alignment across 18 clock domains - critical for synchronous bus interfaces and multi-core synchronization.
Two-clock-source redundancy	LVPECL and LVCMOS inputs allow primary clock + test/backup clock routing, supporting in-system validation and failover design without external multiplexers.
Integrated termination-ready drive	≈23 Ω output impedance allows direct connection to 50Ω series-terminated traces, eliminating discrete series resistors and reducing BOM count and layout area.
Open-pin tolerant inputs	All digital inputs (including LVCMOS_CLK_Sel) feature internal pullup/pulldown resistors, simplifying unused pin handling and improving manufacturing robustness.

Applications

Microprocessor Clock Distribution	FPGA & ASIC Timing Infrastructure
Use Scenario: Distributing a single high-frequency reference clock to multiple Pentium II CPU cores, cache controllers, and memory interfaces on a server motherboard. IC Role / Device Role / Timing Role: Central 1:18 low-skew clock buffer providing synchronized 2.5V LVCMOS clocks with <150 ps inter-output variation. Use Value: Enables simultaneous latching across distributed logic blocks without added timing margin, preserving setup/hold windows in sub-ns timing budgets.	Use Scenario: Driving configuration and user clocks across large FPGA banks and companion ASICs in telecom line cards requiring deterministic phase alignment. IC Role / Device Role / Timing Role: High-fanout LVCMOS clock repeater with selectable LVPECL input for compatibility with backplane-sourced reference clocks. Use Value: Eliminates need for multiple discrete fanout buffers while maintaining trace-length-insensitive skew performance across 10+ clock domains.
Network Processor Synchronization	Test & Validation Clock Tree
Use Scenario: Providing aligned clocks to packet classification engines, traffic managers, and SerDes PHYs in multi-gigabit network processors. IC Role / Device Role / Timing Role: Low-jitter, low-skew distribution node feeding parallel datapaths with matched propagation delays. Use Value: Reduces inter-path timing uncertainty below 200 ps, preventing pipeline stalls and ensuring deterministic packet processing latency.	Use Scenario: Generating parallel test clocks for ATE systems or bench validation of multi-chip modules where stimulus alignment is critical. IC Role / Device Role / Timing Role: Dual-input clock source selector (LVPECL primary, LVCMOS backup) enabling rapid clock domain switching during test sequences. Use Value: Allows functional validation under both production and debug clock conditions without hardware reconfiguration or probe repositioning.

Microprocessor Clock Distribution

FPGA & ASIC Timing Infrastructure

Use Scenario: Distributing a single high-frequency reference clock to multiple Pentium II CPU cores, cache controllers, and memory interfaces on a server motherboard.

IC Role / Device Role / Timing Role: Central 1:18 low-skew clock buffer providing synchronized 2.5V LVCMOS clocks with <150 ps inter-output variation.

Use Value: Enables simultaneous latching across distributed logic blocks without added timing margin, preserving setup/hold windows in sub-ns timing budgets.

Use Scenario: Driving configuration and user clocks across large FPGA banks and companion ASICs in telecom line cards requiring deterministic phase alignment.

IC Role / Device Role / Timing Role: High-fanout LVCMOS clock repeater with selectable LVPECL input for compatibility with backplane-sourced reference clocks.

Use Value: Eliminates need for multiple discrete fanout buffers while maintaining trace-length-insensitive skew performance across 10+ clock domains.

Network Processor Synchronization

Test & Validation Clock Tree

Use Scenario: Providing aligned clocks to packet classification engines, traffic managers, and SerDes PHYs in multi-gigabit network processors.

IC Role / Device Role / Timing Role: Low-jitter, low-skew distribution node feeding parallel datapaths with matched propagation delays.

Use Value: Reduces inter-path timing uncertainty below 200 ps, preventing pipeline stalls and ensuring deterministic packet processing latency.

Use Scenario: Generating parallel test clocks for ATE systems or bench validation of multi-chip modules where stimulus alignment is critical.

IC Role / Device Role / Timing Role: Dual-input clock source selector (LVPECL primary, LVCMOS backup) enabling rapid clock domain switching during test sequences.

Use Value: Allows functional validation under both production and debug clock conditions without hardware reconfiguration or probe repositioning.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MPC9109	Lower-cost 1:10 LVCMOS-only clock driver; no LVPECL input, no dual-supply support, 300 ps max skew.	Suitable for cost-sensitive, lower-fanout applications (<10 loads) with only LVCMOS clock sources and relaxed skew requirements.	Select MPC9109 only when fanout ≤10, skew >300 ps acceptable, and LVPECL interface unnecessary.
MPC942	Enhanced version with lower output impedance (~15 Ω), higher drive capability, and improved skew (≤100 ps); same pinout and function.	Preferred for ultra-low-skew designs requiring <100 ps matching or driving >2 series-terminated lines per output.	MPC942 is a direct upgrade path for designs needing tighter skew or stronger drive; pin-compatible with MPC940LFAR2.

Compared with MPC940LFAR2, MPC9109 reduces functionality and performance for cost savings, while MPC942 improves skew and drive strength within the same footprint - making it a drop-in enhancement for demanding timing-critical upgrades.

Availability

MPC940LFAR2 is available at Aetrix Electronics and suitable for microprocessor clock distribution, FPGA timing infrastructure, network processor synchronization, and test equipment clock tree applications requiring stable component supply and long-term industrial availability.

Supply support for MPC940LFAR2 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

Freescale Semiconductor (now part of NXP Semiconductors) was a leading designer of high-performance analog and mixed-signal ICs, especially for timing, power management, and automotive applications.

The MPC940L family was developed specifically for low-skew, multi-output clock distribution in high-speed computing and communications systems - targeting Pentium II-era microprocessors and early FPGA-based platforms.

FAQ

What input voltage standards does the MPC940LFAR2 support?

The MPC940LFAR2 supports two distinct input standards: differential LVPECL (500–1000 mVpp, common-mode 1.9–2.7 V) and single-ended LVCMOS (VIH ≥ 2.4 V at 3.3V supply, ≥2.0 V at 2.5V supply). Selection is controlled by the LVCMOS_CLK_Sel pin. The MPC940LFAR2 datasheet specifies these thresholds across all valid supply configurations and operating temperatures.

Can the MPC940LFAR2 operate with mixed supply voltages (e.g., 3.3V core and 2.5V outputs)?

Yes - the MPC940LFAR2 explicitly supports mixed-supply operation: VCCI (core) may be 3.3V while VCCO (outputs) is 2.5V, enabling direct interfacing with 2.5V I/O domains of microprocessors like Pentium II. This configuration maintains 150 ps max output-to-output skew and full 250 MHz input frequency capability, as verified in Freescale's DL207 datasheet AC tables.

What is the maximum guaranteed output-to-output skew for MPC940LFAR2?

The MPC940LFAR2 guarantees ≤150 ps maximum output-to-output skew when operated with VCCI = 3.3V and VCCO = 3.3V or 2.5V, over 0°C to 70°C ambient temperature. At VCCI = VCCO = 2.5V, the spec increases to ≤200 ps. These values are production-tested and documented in the AC Characteristics tables of the official Freescale MPC940L datasheet (DL207 Rev 0).

Does MPC940LFAR2 require external termination resistors for 50Ω transmission lines?

No - the MPC940LFAR2 features ≈23 Ω typical output impedance in both HIGH and LOW states, allowing direct connection to 50Ω series-terminated PCB traces without external resistors. Each output can drive two such lines simultaneously, achieving effective 1:36 fanout. This eliminates BOM items and layout complexity while maintaining signal integrity, as confirmed in the device's DC and AC characterization data.

Is MPC940LFAR2 pin-compatible with any newer Freescale/NXP clock distribution ICs?

Yes - the MPC942 is a pin-compatible and functionally enhanced successor to the MPC940LFAR2, offering ≤100 ps output skew and ~15 Ω output impedance. It retains identical pinout, supply configurations, and logic-level compatibility. Migration to MPC942 requires no PCB changes and delivers measurable timing margin improvement in skew-critical applications, per Freescale's migration guidance in AN2291 and MPC942 datasheet.

MPC940LFAR2 Specifications

Product attributes: Attribute value

Manufacturer:: NXP Semiconductors

Series:: -

Package/Case:: 32-LQFP

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Programmable:: Not Verified

PLL:: No

Main Purpose:: Intel CPU Servers

Input:: LVCMOS, LVPECL

Output:: LVCMOS

Number of Circuits:: 1

Ratio - Input:Output:: 2:18

Differential - Input:Output:: Yes/No

Frequency - Max:: 250MHz

Voltage - Supply:: 2.375V ~ 3.465V

Operating Temperature:: 0°C ~ 70°C

Mounting Type:: Surface Mount

Grade:: -

Qualification:: -

Supplier Device Package:: 32-TQFP (7x7)

MPC940LFAR2 FAQ

1.How can I place an order for MPC940LFAR2 through Aetrix?

Please submit a Request for Quotation (RFQ) for MPC940LFAR2 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 MPC940LFAR2 reliable?

The price and inventory of MPC940LFAR2 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MPC940LFAR2 is usually 5 days.

3.What payment methods are accepted for MPC940LFAR2?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MPC940LFAR2 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MPC940LFAR2?

MPC940LFAR2 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MPC940LFAR2 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 MPC940LFAR2?

For technical support, including MPC940LFAR2 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MPC940LFAR2 requirements.

6.How does Aetrix verify that MPC940LFAR2 is sourced from the original manufacturer or authorized distributors?

All MPC940LFAR2 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 MPC940LFAR2 meets industry standards.

7.What is the process for return or replacement of MPC940LFAR2?

All MPC940LFAR2 units undergo pre-shipment inspection (PSI). If there is an issue with MPC940LFAR2, 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 MPC940LFAR2 part is unused and in its original packaging.

Return procedure for MPC940LFAR2:

1.Submit a request within 90 days.

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

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