NXP Semiconductors MPC9351FA

Overview

MPC9351FA from Freescale Semiconductor (formerly Motorola) is a 2.5V/3.3V-compatible, fully integrated PLL-based clock generator delivering nine low-skew LVCMOS clock outputs with configurable divide-by-2/4/8 ratios, up to 200 MHz output frequency, and ≤150 ps output-to-output skew - deployed in PowerQuicc II-based telecom and networking systems requiring precise zero-delay clock distribution.

For engineers reviewing the MPC9351FA datasheet, MPC9351FA pinout, MPC9351FA application, or MPC9351FA equivalent, key selection criteria include its differential LVPECL/LVCMOS dual-reference input support, external feedback capability for zero-delay configuration, VCO frequency range (200–400 MHz), cycle-to-cycle jitter (≤22 ps RMS), and 32-lead LQFP package compatibility with high-density board layouts.

Technical Context

The MPC9351FA employs a fully differential PLL architecture to minimize both cycle-to-cycle and long-term jitter, with VCO operation strictly bounded between 200 MHz and 400 MHz. Its four independent output banks (QA, QB, QC, QD) are individually configured via FSELA–FSELD pins to generate frequency ratios of 4:1, 2:1, 1:1, 1:2, or 1:4 relative to the reference clock.

Operation supports two reference modes: differential LVPECL (PCLK/PCLK) or single-ended LVCMOS (TCLK), selected by REF_SEL; PLL_EN enables static test mode (bypassing PLL), while OE controls output enable/disable with associated loop-open behavior on deassertion. External feedback via EXT_FB - connected to QA, QB, QC, or QD - is mandatory for PLL lock and enables zero-delay buffer functionality.

Key Specifications

Pinout & Package

The MPC9351FA is housed in a 7×7 mm² 32-lead LQFP package (FA suffix, Case 873A–02), with exposed pad not electrically connected. Pin functions are validated per Freescale's official pin configuration table and logic diagram.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ICS8531AGI-01LFT and PI6C557-03LEX, the MPC9351FA uniquely combines differential LVPECL input, external feedback for zero-delay operation, and static test mode - making it irreplaceable in telecom clock trees requiring field-diagnosable PLL behavior and sub-150 ps skew.

Availability

MPC9351FA is available at Aetrix Electronics and suitable for telecom line cards, networking switch fabric, and industrial control backplanes requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MPC9351FA 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) designed high-performance timing solutions for mission-critical communications infrastructure.

The MPC9351FA belongs to Freescale's Timing Solutions product line, engineered specifically for low-skew, zero-delay clock distribution in telecom and networking systems demanding robust jitter performance and dual-voltage compatibility.

FAQ

What is the maximum output frequency supported by the MPC9351FA?

The MPC9351FA supports a maximum output frequency of 200 MHz when configured with ÷2 division from the VCO. This occurs when the VCO operates at its upper limit of 400 MHz and the selected output bank is set to divide-by-2. The device maintains ≤150 ps output-to-output skew and ≤22 ps cycle-to-cycle jitter even at this frequency, making MPC9351FA suitable for high-speed microprocessor clocking in PowerQuicc II systems.

Does the MPC9351FA require external loop filter components?

No, the MPC9351FA does not require external loop filter components. Its PLL is fully integrated with on-chip charge pump and loop compensation. However, an external RC filter is mandatory on the VCCA (analog PLL supply) pin - typically 270 Ω + 10 nF for 3.3V operation - to suppress noise in the 100 kHz–20 MHz band that would otherwise degrade I/O jitter. This requirement is explicitly documented in the Freescale application information section for MPC9351FA.

How does the MPC9351FA achieve zero-delay clock buffering?

The MPC9351FA achieves zero-delay buffering by routing one of its outputs (e.g., QD4) back to the EXT_FB pin to close the PLL feedback loop. The PLL then locks the output edges to the reference clock edge, effectively canceling propagation delay. The residual timing error - static phase offset (t(∅)), output skew (tSK(O)), feedback trace delay, and I/O phase jitter - is bounded to ±351 ps (at 99.7% confidence) in worst-case conditions. This behavior is intrinsic to MPC9351FA's architecture and verified in Freescale's zero-delay application diagrams.

What are the valid reference clock input options for the MPC9351FA?

The MPC9351FA accepts two reference clock types: differential LVPECL via PCLK/PCLK pins (250–1000 mVpp, common-mode 1.0–(VCC−0.6) V) or single-ended LVCMOS via TCLK (25–200 MHz, VIH ≥2.0 V at 3.3V). The REF_SEL pin selects between them - pulled low for PCLK/PCLK, pulled high for TCLK. Both inputs are LVCMOS-compatible in logic level, but only PCLK/PCLK supports the full 200 MHz reference frequency range; TCLK is limited to 200 MHz only in static test mode.

Can the MPC9351FA drive multiple transmission lines from a single output?

Yes, each MPC9351FA output can drive either one 50 Ω parallel-terminated transmission line (to VTT = VCC/2) or up to two 50 Ω series-terminated lines. In dual-series mode, the output impedance (~14 Ω) plus optimized series resistors (e.g., 22 Ω each) matches the effective 25 Ω load, enabling 1:18 effective fanout. Simulation data in the MPC9351FA datasheet confirms <43 ps timing delta between single- and dual-loaded outputs, preserving skew integrity without layout penalties.