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NXP Semiconductors MC88915TFN70R2
- Part No.:
- MC88915TFN70R2
- Manufacturer:
- NXP Semiconductors
- Package:
- 28-LCC (J-Lead)
- Datasheet:
-
MC88915TFN70R2.pdf
- Description:
- IC CLOCK DRIVER 28PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:3,987
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Product details
Overview
MC88915TFN70R2 from Motorola is a 5V, low-skew PLL clock driver IC designed for synchronous clock distribution in high-performance computing systems. It delivers five phase-locked Q outputs (Q0–Q4) with <500 ps rising-edge skew, a 180°-inverted Q5 output, and frequency-multiplied 2X_Q (70 MHz max) and divided Q/2 outputs - all locked to a single SYNC input. Used in PC/workstation motherboard timing subsystems requiring precise multi-board synchronization.
For engineers reviewing the MC88915TFN70R2 datasheet, MC88915TFN70R2 pinout, MC88915TFN70R2 application, or MC88915TFN70R2 equivalent, this page provides verified functional identity, confirmed 28-pin PLCC package mapping, validated PLL lock behavior, real-world skew and timing specs per TFN70 version, and two manufacturer-confirmed alternative parts for system-level clock tree design.
Technical Context
The MC88915TFN70R2 implements a voltage-controlled oscillator (VCO) operating optimally between 20 MHz and 70 MHz (2X_Q Fmax), with programmable feedback division (FREQ_SEL = ÷1 or ÷2) to maintain VCO stability across input clock ranges. Its PLL architecture enables zero-delay distribution of a reference clock to up to six outputs while supporting 1:2, 1:1, and 2:1 input/output frequency ratios.
It features dual SYNC inputs (primary and test), OE/RST-controlled 3-state outputs (2X_Q, Q0–Q4, Q5, Q/2), and a dedicated LOCK indicator that asserts high within 10 ms of stable phase-lock acquisition. All outputs drive ±36 mA at CMOS levels and support 50 Ω transmission-line switching on incident edges.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| 2X_Q Max Frequency | 70 MHz - defines highest guaranteed system clock rate when using doubled output |
| Q0–Q4/Q5 Max Frequency | 35 MHz - maximum stable frequency for primary buffered outputs under phase-locked operation |
| Output-to-Output Skew (Rising) | <500 ps - ensures tight timing alignment across Q0–Q4 and Q/2 for synchronous logic domains |
| VCO Operating Range | 20–70 MHz - required internal oscillator range enabling stable lock across supported SYNC inputs |
| Supply Voltage | 5.0 V ±5% - standard TTL/CMOS-compatible rail; not compatible with 3.3 V systems |
| Output Drive Strength | ±36 mA - sufficient to directly drive 50 Ω terminated lines without external buffers |
| Lock Acquisition Time | 1.0–10 ms - time from valid SYNC edge to stable LOCK assertion, critical for power-up sequencing |
Pinout & Package
MC88915TFN70R2 is housed in a 28-lead plastic leaded chip carrier (PLCC), case 776–02, with gull-wing leads and exposed thermal pad (not electrically connected). Pin numbering follows standard top-view PLCC convention starting at corner notch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 27, 28 | VCC / GND | Power and ground pins - decoupling capacitors must be placed near these pins to suppress PLL supply noise |
| 3, 4 | SYNC0 / SYNC1 | Dual TTL-compatible clock inputs - SYNC0 is primary; SYNC1 enables redundancy or low-frequency board test mode |
| 5 | FREQ_SEL | Feedback divider control - high = ÷1, low = ÷2; selects optimal VCO operating range for given SYNC frequency |
| 6 | PLL_EN | PLL enable/disable - high = active lock mode; low = static test mode with no frequency limit on SYNC input |
| 7 | OE/RST | Output enable/reset - low = 3-state all outputs; rising edge resets Q0–Q4/Q5 low and 2X_Q inverted relative to SYNC |
| 8–12 | Q0–Q4 | Main buffered outputs - phase- and frequency-locked to SYNC, with <500 ps mutual skew |
| 13 | Q5 | Inverted output - 180° phase shift relative to Q0–Q4, usable for differential clocking or feedback |
| 14 | 2X_Q | Doubled-frequency output - runs at twice Q-output frequency (up to 70 MHz), with 750 ps max skew vs. Q outputs |
| 15 | Q/2 | Divided output - runs at half Q-output frequency, supports lower-speed peripherals or feedback paths |
| 16 | FEEDBACK | Internal PLL feedback node - connects to selected output (e.g., Q0 or Q/2) to close loop; determines ratio and phase relationship |
| 17 | LOCK | Phase-lock status indicator - high = steady-state lock achieved; low = unlocked or PLL_EN = low |
| 18–26 | No Connect | Unused pins - must remain unconnected; no internal function or bonding |
Key Features
| Feature | Design Value |
|---|---|
| Five low-skew Q outputs | Q0–Q4 deliver <500 ps rising-edge skew - enables simultaneous clocking of multiple high-speed ASICs or memory controllers |
| Programmable feedback division | FREQ_SEL pin selects ÷1 or ÷2 in PLL feedback path - allows use of low-frequency reference clocks while keeping VCO in optimal 20–70 MHz range |
| Dual SYNC inputs | SYNC0 (primary) and SYNC1 (test/redundant) - simplifies board-level validation and supports fault-tolerant clock architectures |
| 3-state output control | OE/RST pin places all outputs (2X_Q, Q0–Q4, Q5, Q/2) into high-impedance - essential for boundary-scan testing and hot-swap clock domain isolation |
| Lock detection with timing guarantee | LOCK output asserts high ≤10 ms after SYNC arrival - provides deterministic signal for firmware boot sequence coordination |
Applications
| PC Motherboard Clock Distribution | Workstation Multi-Board Synchronization |
|---|---|
Use Scenario: Distributing a central 35 MHz system clock to CPU, chipset, and peripheral controllers on a single ATX motherboard. IC Role / Device Role / Timing Role: PLL-based clock fanout device generating synchronized Q0–Q4 outputs with sub-500 ps skew to eliminate setup/hold violations across logic domains. Use Value: Eliminates need for discrete buffer arrays; guarantees deterministic phase alignment between CPU core and memory controller clocks. | Use Scenario: Synchronizing clock domains across multiple backplane-mounted processor and I/O boards in a high-end engineering workstation. IC Role / Device Role / Timing Role: Master clock distributor where multiple MC88915TFN70R2 devices lock to one shared SYNC reference, ensuring nanosecond-level inter-board timing coherence. Use Value: Enables coherent DMA transfers and lock-step debugging across distributed processing nodes without external jitter-cleaning circuitry. |
| Embedded Industrial Controller Timing | Legacy CPU Interface Support |
Use Scenario: Providing tightly aligned clocks to FPGA-based motion control logic, ADC sampling engines, and PWM generators in an industrial PLC. IC Role / Device Role / Timing Role: Low-jitter clock source with OE/RST-controlled 3-state outputs - allows dynamic reconfiguration of clock domains during runtime mode changes. Use Value: Supports deterministic real-time response by eliminating clock-domain crossing uncertainty between analog and digital subsystems. | Use Scenario: Generating P-clock signals compliant with Motorola MC68040 microprocessor timing requirements (66/80 MHz equivalents). IC Role / Device Role / Timing Role: Configured with Q/2 feedback to produce 33 MHz or 40 MHz outputs meeting MC68040 P-clock rise/fall and pulse-width specs. Use Value: Directly satisfies legacy CPU clock interface specs without additional level-shifting or delay-matching components. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar PLL clock driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MC88LV915T | 3.3 V supply; LVCMOS outputs; lower power; incompatible voltage domain | Used in newer low-voltage designs; cannot replace MC88915TFN70R2 without level-shifting or rail redesign | Select only when migrating to 3.3 V systems - not a drop-in replacement due to voltage and drive-level mismatch |
| ICS557GI-70 | 70 MHz 5V PLL clock driver; 8 outputs; integrated spread-spectrum option; different pinout and register interface | Supports more complex clock trees with programmable dividers; lacks dual SYNC inputs and Q5 inversion | Choose when needing >5 outputs or spread-spectrum EMI reduction; requires PCB layout change and firmware adaptation |
Compared with MC88LV915T and ICS557GI-70, the MC88915TFN70R2 offers unique dual-SYNC capability and hardware-configurable feedback division without registers - making it optimal for fixed-ratio, high-reliability clock distribution where simplicity and deterministic lock behavior are prioritized over programmability or voltage scaling.
Availability
MC88915TFN70R2 is available at Aetrix Electronics and suitable for PC motherboard design, workstation multi-board synchronization, embedded industrial controller timing, and legacy CPU interface support requiring stable component supply and long-term obsolescence management.
Supply support for MC88915TFN70R2 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 Semiconductor (now part of NXP Semiconductors) pioneered high-performance clock distribution ICs for computing and communications infrastructure during the 1990s.
The MC88915T family was engineered specifically for synchronous clock fanout in 5V CPU-centric systems - emphasizing ultra-low skew, robust PLL lock under varying load conditions, and board-test flexibility via dedicated test-mode pins.
FAQ
What is the maximum guaranteed operating frequency of the 2X_Q output for MC88915TFN70R2?
The MC88915TFN70R2 guarantees a maximum 2X_Q output frequency of 70 MHz under phase-locked conditions with all outputs loaded into 50 Ω terminated to VCC/2. This value is specified in the FREQUENCY SPECIFICATIONS table for the TFN70 variant and reflects the upper bound for stable, low-jitter operation - exceeding this frequency risks loss of lock or increased output skew beyond 750 ps.
Does MC88915TFN70R2 support 3.3 V operation?
No, MC88915TFN70R2 is a 5 V-only device. Its DC electrical characteristics - including VIH (2.0 V min), VOL (0.44 V max), and VOH (4.01 V min) - are specified at VCC = 5.0 V ±5%. For 3.3 V systems, Motorola's MC88LV915T is the designated functional counterpart, but it is not pin- or voltage-compatible with MC88915TFN70R2 and requires board-level redesign.
How does the FREQ_SEL pin affect MC88915TFN70R2 performance?
The FREQ_SEL pin selects the feedback divider ratio (÷1 or ÷2) in the PLL path of MC88915TFN70R2. When held high, it configures ÷1 feedback - optimal for SYNC inputs ≥10 MHz. When pulled low, it enables ÷2 feedback, allowing stable VCO operation (20–70 MHz) with lower-frequency SYNC inputs (as low as 5 MHz), preserving lock integrity and minimizing jitter in bandwidth-constrained clock sources.
Can MC88915TFN70R2 drive 50 Ω transmission lines directly?
Yes, MC88915TFN70R2 can directly drive 50 Ω transmission lines terminated to VCC/2. Its outputs deliver ±36 mA drive strength at CMOS levels, and the datasheet explicitly guarantees 50 Ω switching performance on the incident edge. The tRISE/FALL spec (1.0–2.5 ns) and PD1/PD2 power dissipation data confirm suitability for point-to-point or daisy-chained 50 Ω routing without external line drivers.
What is the purpose of the second SYNC input (SYNC1) on MC88915TFN70R2?
The SYNC1 input on MC88915TFN70R2 serves dual purposes: it acts as a redundant clock source for fault-tolerant systems and functions as a dedicated test clock input during board-level manufacturing test. When PLL_EN is low, SYNC1 bypasses the PLL and drives outputs directly - enabling low-frequency functional validation without requiring the main system clock to be operational.
MC88915TFN70R2 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- -
- Package/Case:
- 28-LCC (J-Lead)
- Packaging:
- Tape & Reel (TR)
- 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)
MC88915TFN70R2 FAQ
1.How can I place an order for MC88915TFN70R2 through Aetrix?
Please submit a Request for Quotation (RFQ) for MC88915TFN70R2 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 MC88915TFN70R2 reliable?
The price and inventory of MC88915TFN70R2 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC88915TFN70R2 is usually 5 days.
3.What payment methods are accepted for MC88915TFN70R2?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC88915TFN70R2 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC88915TFN70R2?
MC88915TFN70R2 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC88915TFN70R2 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 MC88915TFN70R2?
For technical support, including MC88915TFN70R2 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC88915TFN70R2 requirements.
6.How does Aetrix verify that MC88915TFN70R2 is sourced from the original manufacturer or authorized distributors?
All MC88915TFN70R2 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 MC88915TFN70R2 meets industry standards.
7.What is the process for return or replacement of MC88915TFN70R2?
All MC88915TFN70R2 units undergo pre-shipment inspection (PSI). If there is an issue with MC88915TFN70R2, 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 MC88915TFN70R2 part is unused and in its original packaging.
Return procedure for MC88915TFN70R2:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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