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Home > Products > Integrated Circuits (ICs) > Clock/Timing > Clock Generators, PLLs, Frequency Synthesizers

NXP Semiconductors MC88915FN70

Name: MC88915FN70
Brand: NXP Semiconductors
SKU: MC88915FN70
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MC88915FN70

Manufacturer:: NXP Semiconductors

Category:: Clock Generators, PLLs, Frequency Synthesizers

Package:: 28-LCC (J-Lead)

Datasheet:: MC88915FN70.pdf

Description:: IC CLOCK DRIVER 28PLCC

Quantity:: RFQ Add To RFQ list

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Product details

Overview

MC88915FN70 from Motorola is a phase-locked loop (PLL) clock driver IC designed for high-performance PC and workstation clock distribution. It delivers five low-skew Q outputs (Q0–Q4) with <500 ps rising-edge skew, a 180°-phase-inverted Q5 output, a 2× frequency 2X_Q output (70 MHz max), and a Q/2 output - all locked to a single SYNC input. It supports input/output frequency ratios of 2:1, 1:1, and 1:2 and operates across 5–35 MHz (Q outputs) or up to 70 MHz (2X_Q), enabling local clock multiplication and synchronous multi-board distribution.

For engineers reviewing the MC88915FN70 datasheet, MC88915FN70 pinout, MC88915FN70 application, or MC88915FN70 equivalent, this device is selected for precise, low-jitter clock fanout in systems requiring deterministic phase alignment, board-level testability via PLL_EN test mode, and flexible feedback configuration using FREQ_SEL to maintain VCO operation above 20 MHz.

Technical Context

The MC88915FN70 implements a charge-pump PLL with voltage-controlled oscillator (VCO) optimized for 20–70 MHz operation. Its feedback path includes programmable divide-by-1 or divide-by-2 (via FREQ_SEL), enabling three input-to-Q-output frequency relationships: 1:2, 1:1, and 2:1. The PLL locks rising edges of Q outputs to SYNC, with tPD (SYNC-to-FEEDBACK delay) ranging from –1.05 ns to –0.50 ns depending on RC1 biasing.

It features dual SYNC inputs (SYNC[0], SYNC[1]) selectable via REF_SEL, asynchronous RST (active-low), and LOCK indicator (open-drain, for passive monitoring only). All outputs drive ±36 mA at CMOS levels and interface directly with TTL/CMOS loads; inputs are TTL-compatible. The analog section (RC1, VCC(AN), GND(AN)) requires external loop filtering per Figure 6 to suppress jitter.

Key Specifications

Parameter	Value and Actual Design Meaning
2X_Q Max Frequency	70 MHz - defines upper limit for doubled-frequency output used in high-speed CPU/memory clock domains
Q Output Max Frequency	35 MHz - maximum guaranteed frequency for Q0–Q4/Q5 outputs under phase-locked, 50 pF load conditions
Output-to-Output Skew (Q0–Q4)	<500 ps rising-edge - ensures timing-critical parallel bus or memory interface synchronization
Input Voltage Compatibility	TTL-level inputs (VIH ≥2.0 V, VIL ≤0.8 V) - enables direct interfacing with legacy logic without level-shifting
Output Drive Strength	±36 mA at CMOS levels - sufficient to drive 50 Ω terminated lines or multiple TTL inputs without buffers
VCO Optimal Range	20–70 MHz - mandates FREQ_SEL selection to keep VCO within stable, low-jitter operating band
Lock Acquisition Time	1–10 ms - determines minimum system boot or clock-switching latency before stable outputs available

Pinout & Package

MC88915FN70 is housed in a 28-lead plastic PLCC (Package Code FN, Case 776–02), measuring 11.43 mm × 11.43 mm × 0.81 mm, with gull-wing leads and internal analog/digital power separation (VCC/GND pins designated for logic; VCC(AN)/GND(AN) for PLL analog section).

Pin/Terminal	Circuit Role	Design Meaning
SYNC[0], SYNC[1]	Reference clock inputs	Dual TTL-compatible clock sources; REF_SEL selects active input for PLL reference
FREQ_SEL	Feedback divider control	High = ÷1, Low = ÷2 in PLL feedback path - adjusts VCO frequency to stay ≥20 MHz
FEEDBACK	PLL phase detector input	Accepts Q/2, Q0–Q4, Q5, or 2X_Q for closed-loop locking - determines final output frequency ratio
Q0–Q4	Main clock outputs	Five identical, phase-aligned CMOS outputs with <500 ps mutual skew - for parallel bus or multi-chip clocking
Q5	Inverted clock output	180° phase-shifted version of Q0–Q4 - supports differential clocking or complementary logic timing
2X_Q	Doubled-frequency output	Runs at twice Q-output frequency (up to 70 MHz) - feeds high-speed CPU cores or memory controllers
Q/2	Halved-frequency output	Runs at half Q-output frequency - provides lower-speed peripheral or control-domain clocks
LOCK	Phase-lock status indicator	Open-drain output asserted high when PLL achieves steady-state lock - for passive monitoring only
RST	Asynchronous reset	Active-low signal forcing all outputs low - used for system initialization or fault recovery
PLL_EN	PLL enable/disable	Pulling low disables VCO and enters low-frequency test mode - allows board-level validation below 5 MHz
RC1	External loop filter node	Connects to 470 kΩ resistor (to VCC(AN) or GND(AN)) and 0.1 µF capacitor - sets PLL loop dynamics and jitter performance

Key Features

Feature	Design Value
Programmable feedback division	FREQ_SEL pin selects ÷1 or ÷2 in PLL feedback path - enables optimal VCO operation across wide input frequency range (5–35 MHz)
Dual reference clock inputs	SYNC[0] and SYNC[1] with REF_SEL selection - supports redundancy, test clock injection, or multi-source clock switching
Test mode with full-frequency coverage	PLL_EN = low disables VCO and enables direct clock pass-through/division - permits functional testing at sub-MHz frequencies on ATE
Low-jitter analog PLL architecture	RC1-based external loop filter with dedicated analog supply pins (VCC(AN)/GND(AN)) - isolates VCO from digital noise, limiting phase deviation to ≤250 ps under 250 mV VCC step
Multi-ratio synchronized outputs	Simultaneous Q (1×), Q/2 (0.5×), 2X_Q (2×), and Q5 (inverted 1×) - eliminates need for external dividers/multipliers in hierarchical clock trees

Applications

Workstation CPU Clock Distribution	Multi-Board Synchronous Systems
Use Scenario: Distributing a central 25 MHz system clock to multiple CPU cards and memory modules while maintaining sub-nanosecond inter-board skew. IC Role / Device Role / Timing Role: PLL clock driver generating synchronized 50 MHz (2X_Q) and 25 MHz (Q) outputs across physically separated boards via common SYNC reference. Use Value: Enables deterministic phase alignment between CPU, cache, and memory controllers across backplane-connected cards - critical for coherent multiprocessing.	Use Scenario: Providing phase-locked clocks to a cluster of embedded controller boards sharing one master oscillator, where trace-length mismatches would otherwise cause timing violations. IC Role / Device Role / Timing Role: Local clock regeneration node that locks each board's Q outputs to the same SYNC signal - eliminating cumulative PCB trace skew. Use Value: Reduces worst-case inter-board output-to-output skew to ≤1.2 ns (measured at pins), preserving setup/hold margins in distributed real-time control systems.
PC Motherboard High-Speed Bus Timing	Legacy System Board-Level Test
Use Scenario: Driving PCI or ISA bus clock domains requiring tightly aligned 33 MHz or 8.33 MHz clocks with minimal duty-cycle distortion. IC Role / Device Role / Timing Role: Fanout buffer delivering Q0–Q4 at 33 MHz (FN70 grade) with <500 ps skew and ±36 mA drive - directly loading multiple bus transceivers. Use Value: Eliminates need for discrete clock buffers and external termination networks - simplifies layout and guarantees timing compliance across temperature (0°C to +70°C).	Use Scenario: Validating clock tree functionality during manufacturing test using low-speed ATE (<1 MHz) incapable of achieving PLL lock. IC Role / Device Role / Timing Role: Entering test mode (PLL_EN = low) to generate predictable divided outputs (e.g., Q/2 = ÷4, 2X_Q = inverted) from any applied test clock. Use Value: Allows full functional verification of clock routing and fanout without requiring high-frequency test equipment - reducing test cost and cycle time.

Workstation CPU Clock Distribution

Multi-Board Synchronous Systems

Use Scenario: Distributing a central 25 MHz system clock to multiple CPU cards and memory modules while maintaining sub-nanosecond inter-board skew.

IC Role / Device Role / Timing Role: PLL clock driver generating synchronized 50 MHz (2X_Q) and 25 MHz (Q) outputs across physically separated boards via common SYNC reference.

Use Value: Enables deterministic phase alignment between CPU, cache, and memory controllers across backplane-connected cards - critical for coherent multiprocessing.

Use Scenario: Providing phase-locked clocks to a cluster of embedded controller boards sharing one master oscillator, where trace-length mismatches would otherwise cause timing violations.

IC Role / Device Role / Timing Role: Local clock regeneration node that locks each board's Q outputs to the same SYNC signal - eliminating cumulative PCB trace skew.

Use Value: Reduces worst-case inter-board output-to-output skew to ≤1.2 ns (measured at pins), preserving setup/hold margins in distributed real-time control systems.

PC Motherboard High-Speed Bus Timing

Legacy System Board-Level Test

Use Scenario: Driving PCI or ISA bus clock domains requiring tightly aligned 33 MHz or 8.33 MHz clocks with minimal duty-cycle distortion.

IC Role / Device Role / Timing Role: Fanout buffer delivering Q0–Q4 at 33 MHz (FN70 grade) with <500 ps skew and ±36 mA drive - directly loading multiple bus transceivers.

Use Value: Eliminates need for discrete clock buffers and external termination networks - simplifies layout and guarantees timing compliance across temperature (0°C to +70°C).

Use Scenario: Validating clock tree functionality during manufacturing test using low-speed ATE (<1 MHz) incapable of achieving PLL lock.

IC Role / Device Role / Timing Role: Entering test mode (PLL_EN = low) to generate predictable divided outputs (e.g., Q/2 = ÷4, 2X_Q = inverted) from any applied test clock.

Use Value: Allows full functional verification of clock routing and fanout without requiring high-frequency test equipment - reducing test cost and cycle time.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
ICS8302AMLF	LVDS outputs, 3.3 V supply, no integrated PLL - requires external crystal oscillator and lacks frequency multiplication	Suitable for low-noise, point-to-point clock distribution but cannot replace MC88915FN70's local 2× multiplication or test-mode functionality	Select when system uses LVDS signaling and external clock source; not drop-in for PLL-based architectures.
PI6C20400LEX	Integrated crystal oscillator input, 1.8/2.5/3.3 V operation, 8 outputs - higher channel count but no Q5 inversion or programmable feedback division	Better suited for modern low-voltage SoC clock trees; lacks analog loop filter tuning and legacy TTL compatibility	Prefer for new designs targeting power efficiency and integration; avoid when backward compatibility with 5 V TTL or RC1-based jitter control is required.

Compared with ICS8302AMLF and PI6C20400LEX, the MC88915FN70 uniquely combines 5 V TTL compatibility, on-chip PLL-based frequency multiplication (2×/1×/0.5×), programmable feedback division, and dedicated test-mode support - making it irreplaceable in legacy high-performance computing clock trees requiring deterministic phase control and board-level validation flexibility.

Availability

MC88915FN70 is available at Aetrix Electronics and suitable for workstation CPU clock distribution, multi-board synchronous systems, PC motherboard high-speed bus timing, and legacy system board-level test requiring stable component supply and long-term obsolescence management.

Supply support for MC88915FN70 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

Motorola (now part of NXP Semiconductors) was a pioneering semiconductor manufacturer known for high-reliability timing, microcontroller, and analog products serving computing and industrial markets.

The MC88915 belongs to Motorola's Timing Solutions product line, engineered specifically for low-skew, PLL-based clock distribution in high-performance computing platforms where deterministic phase alignment and multi-board synchronization were critical design requirements.

FAQ

What is the maximum guaranteed frequency for the Q outputs of the MC88915FN70?

The MC88915FN70 guarantees Q0–Q4 and Q5 outputs up to 35 MHz when operating in phase-locked condition with 50 pF load. This rating is derived from the 70 MHz 2X_Q maximum specification and the 1:1 or 2:1 input-to-output frequency relationships supported by the device's PLL architecture.

How does the FREQ_SEL pin affect the MC88915FN70's operation?

The FREQ_SEL pin selects the feedback divider ratio in the MC88915FN70's PLL: high enables divide-by-1, low enables divide-by-2. This adjustment ensures the VCO operates within its optimal 20–70 MHz range - for example, a 10 MHz SYNC input with FREQ_SEL low yields a 20 MHz VCO frequency, satisfying stability and jitter requirements.

Can the LOCK output of the MC88915FN70 be used to control other circuitry?

No - the LOCK output of the MC88915FN70 is intended solely for passive monitoring or evaluation. Motorola explicitly states it should not drive active circuitry because it may remain low even when phase-locked under certain conditions, making it unreliable for control signaling.

What package type is used for the MC88915FN70, and what are its key mechanical dimensions?

The MC88915FN70 uses a 28-lead plastic PLCC (FN suffix, Case 776–02) measuring 11.43 mm × 11.43 mm × 0.81 mm. It features gull-wing leads, separate analog/digital power pins (VCC(AN)/GND(AN)), and is specified for surface-mount assembly with standard PLCC reflow profiles.

Why does the MC88915FN70 include two SYNC inputs and a REF_SEL pin?

The MC88915FN70 includes SYNC[0] and SYNC[1] inputs with REF_SEL selection to support clock redundancy, test clock injection, or dynamic clock source switching. During board-level test, REF_SEL can route a low-frequency test clock to SYNC[0], while in normal operation it selects the primary system oscillator connected to SYNC[1].

MC88915FN70 Specifications

Product attributes: Attribute value

Manufacturer:: NXP Semiconductors

Series:: -

Package/Case:: 28-LCC (J-Lead)

Packaging:: Tube

Product Status:: Obsolete

Programmable:: Not Verified

Type:: Clock Driver, Fanout Distribution, Multiplexer

PLL:: Yes

Input:: TTL

Output:: CMOS, TTL

Number of Circuits:: 1

Ratio - Input:Output:: 3:8

Differential - Input:Output:: No/No

Frequency - Max:: 70MHz

Divider/Multiplier:: Yes/Yes

Voltage - Supply:: 4.75V ~ 5.25V

Operating Temperature:: 0°C ~ 70°C

Mounting Type:: Surface Mount

Grade:: -

Qualification:: -

Supplier Device Package:: 28-PLCC (11.51x11.51)

MC88915FN70 FAQ

1.How can I place an order for MC88915FN70 through Aetrix?

Please submit a Request for Quotation (RFQ) for MC88915FN70 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 MC88915FN70 reliable?

The price and inventory of MC88915FN70 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC88915FN70 is usually 5 days.

3.What payment methods are accepted for MC88915FN70?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC88915FN70 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MC88915FN70?

MC88915FN70 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MC88915FN70 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 MC88915FN70?

For technical support, including MC88915FN70 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC88915FN70 requirements.

6.How does Aetrix verify that MC88915FN70 is sourced from the original manufacturer or authorized distributors?

All MC88915FN70 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 MC88915FN70 meets industry standards.

7.What is the process for return or replacement of MC88915FN70?

All MC88915FN70 units undergo pre-shipment inspection (PSI). If there is an issue with MC88915FN70, 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 MC88915FN70 part is unused and in its original packaging.

Return procedure for MC88915FN70:

1.Submit a request within 90 days.

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

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