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NXP Semiconductors MC88915TFN70
- Part No.:
- MC88915TFN70
- Manufacturer:
- NXP Semiconductors
- Package:
- 28-LCC (J-Lead)
- Datasheet:
-
MC88915TFN70.pdf
- Description:
- IC CLOCK DRIVER 28PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:4,870
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Product details
Overview
MC88915TFN70 from Motorola is a 5V, low-skew PLL clock driver IC designed for synchronous clock distribution in high-performance PC and workstation systems. It delivers five phase-locked Q outputs (Q0–Q4) with <500 ps rising-edge skew, one inverted Q5 output, plus 2X_Q (70 MHz max) and Q/2 outputs - all locked to a single SYNC input. Its FREQ_SEL pin enables programmable feedback division (÷1 or ÷2) to maintain VCO operation within its optimal 20–70 MHz range.
For engineers reviewing the MC88915TFN70 datasheet, MC88915TFN70 pinout, MC88915TFN70 application, or MC88915TFN70 equivalent, key selection considerations include guaranteed 70 MHz 2X_Q output frequency, ±36 mA CMOS/TTL-compatible drive strength, 3-state OE/RST control, LOCK indicator status, and PLCC-28 package compatibility with legacy Motorola clock distribution designs.
Technical Context
The MC88915TFN70 implements a fully integrated PLL architecture with internal VCO, phase detector, and feedback divider. It supports three input/output frequency ratios (2:1, 1:1, 1:2) via selectable feedback paths - including Q/2, Q0–Q4, Q5, or 2X_Q - enabling flexible system clock synthesis from a low-frequency reference. The FREQ_SEL pin selects between ÷1 and ÷2 feedback division to keep the VCO operating between 20 MHz and 70 MHz.
It features dual SYNC inputs: primary SYNC for normal operation and secondary SYNC for test-mode clock injection when PLL_EN is low. In static test mode (PLL_EN = low), the device accepts arbitrary low-frequency clocks without PLL constraints, while OE/RST forces all outputs into high-impedance state for board-level testing. The LOCK output asserts high within 10 ms of stable SYNC and full VCC.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| 2X_Q Max Frequency | 70 MHz - defines highest usable system clock rate when using doubled output |
| Q0–Q4/Q5 Max Frequency | 35 MHz - maximum guaranteed frequency for primary buffered outputs under phase-lock |
| Output-to-Output Skew (Rising) | <500 ps - ensures tight timing alignment across Q0–Q4 and Q/2 for synchronous logic domains |
| Drive Strength | ±36 mA - sufficient to directly drive 50 Ω transmission lines terminated at VCC/2 |
| Supply Voltage | 5.0 V ±5% - requires standard 5V rail; not compatible with 3.3V systems (see MC88LV915T for 3.3V version) |
| Operating Temperature | 0°C to +70°C - commercial-grade rating suitable for desktop PC and non-industrial workstation use |
| Input Compatibility | TTL-level - accepts standard 0.8 V / 2.0 V logic thresholds on SYNC, PLL_EN, OE/RST, and FREQ_SEL pins |
Pinout & Package
MC88915TFN70 uses a 28-lead plastic leaded chip carrier (PLCC) package, case 776–02, with gull-wing leads and exposed die pad. Pin numbering follows standard top-view PLCC convention (pin 1 marked by corner notch).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 27, 28 | VCC / GND Power Pins | Dual VCC (pins 1, 28) and dual GND (pins 2, 27) reduce supply noise and improve PSRR for clock integrity |
| 3, 4 | SYNC0 / SYNC1 Inputs | Primary and secondary TTL-compatible clock inputs; SYNC1 used for test-mode injection when PLL_EN = low |
| 5 | FREQ_SEL | Feedback divider select: high = ÷1, low = ÷2 - enables VCO tuning to stay within optimal 20–70 MHz range |
| 6 | PLL_EN | PLL enable/disable: high = active lock mode, low = static test mode with unrestricted input frequency |
| 7 | OE/RST | Output enable/reset: low = 3-state all outputs (2X_Q, Q0–Q4, Q5, Q/2); rising edge resets Q outputs to low |
| 8 | LOCK | Open-drain status output: high = steady-state phase/frequency lock achieved; low = unlocked or PLL_EN = low |
| 9–13 | Q0–Q4 Outputs | Five identical CMOS/TTL-compatible outputs, phase- and frequency-locked to SYNC with <500 ps skew |
| 14 | Q5 Output | Inverted (180° phase shift) version of Q0–Q4 outputs - useful for differential clocking or complementary logic |
| 15 | 2X_Q Output | Frequency-doubled output running at twice Q-output rate (up to 70 MHz); rise/fall time ≤2.5 ns into 50 Ω |
| 16 | Q/2 Output | Frequency-divided-by-two output; provides half-rate synchronized clock for lower-speed subsystems |
| 17 | FEEDBACK Input | Internal feedback path input - connected to selected output (e.g., Q0 or Q/2) to close PLL loop per configuration |
| 18–26 | No Connect (NC) | Unused internal pins - must be left unconnected per Motorola design; no tie-to-rail or bypass required |
Key Features
| Feature | Design Value |
|---|---|
| Programmable Feedback Division | FREQ_SEL pin selects ÷1 or ÷2 feedback ratio - maintains VCO in optimal 20–70 MHz range regardless of input clock frequency |
| Multi-Output Clock Synthesis | Simultaneous generation of 2X_Q (70 MHz), Q0–Q4 (35 MHz), Q5 (inverted), and Q/2 (17.5 MHz) from single SYNC source |
| Test-Ready Architecture | Dual SYNC inputs + PLL_EN and OE/RST pins enable full-board functional test without external clock generators |
| Low-Skew Distribution | <500 ps output-to-output skew among Q0–Q4 ensures deterministic timing across multi-chip synchronous buses |
| Robust Drive Capability | ±36 mA output drive supports direct 50 Ω transmission line switching - eliminates need for external buffers in most PC motherboard layouts |
Applications
| Desktop PC Motherboard Clock Tree | Workstation Multi-Processor Synchronization |
|---|---|
Use Scenario: Distributing a central 35 MHz system clock to CPU, chipset, and peripheral controllers on an ATX motherboard. IC Role / Device Role / Timing Role: Primary PLL-based clock fanout buffer generating synchronized Q0–Q4 outputs and 2X_Q for AGP/PCI-X interfaces. Use Value: Eliminates discrete oscillator + buffer combinations; guarantees sub-500 ps skew across 5 critical clock domains under thermal and voltage variation. |
Use Scenario: Aligning clock edges across multiple CPU modules and memory banks in a dual-processor RISC workstation. IC Role / Device Role / Timing Role: Synchronous clock distributor locking multiple MC88915T devices to a common SYNC reference for inter-processor coherence. Use Value: Enables deterministic inter-processor communication with zero accumulated jitter across boards - verified via LOCK signal monitoring. |
| Legacy Industrial Control Backplane | Embedded Test Equipment Timing Subsystem |
Use Scenario: Replacing aging discrete clock solutions in a VMEbus-based PLC controller requiring long-term component availability. IC Role / Device Role / Timing Role: High-reliability 5V clock driver delivering Q/2 (17.5 MHz) and Q0–Q4 to FPGA-configured I/O modules. Use Value: Maintains backward compatibility with existing PLCC-28 footprints and 5V logic families while improving skew and jitter performance. |
Use Scenario: Providing controllable, 3-state-capable clock signals during automated functional test of digital ASICs on handler-based ATE. IC Role / Device Role / Timing Role: Test-mode clock generator activated via PLL_EN = low and OE/RST toggling to inject known-edge clocks without PLL constraints. Use Value: Reduces test fixture complexity by eliminating external pattern generators - SYNC1 input accepts arbitrary low-frequency test clocks. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar PLL clock driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MC88915TFN55 | Lower 2X_Q max frequency (55 MHz vs. 70 MHz); same PLCC-28 package and pinout; identical AC/DC specs except frequency limits | Valid for 27.5 MHz Q-output systems where 70 MHz headroom is unnecessary; rated for –40°C to +85°C industrial temp range | Select MC88915TFN55 only if system clock requirements are ≤27.5 MHz and extended temperature operation is required. |
| ICS557GI-70LF | 70 MHz 2X_Q output; 32-pin TSSOP package; supports 3.3V/5V dual supply; includes spread-spectrum option not present in MC88915TFN70 | Targets modern low-voltage designs; lacks dual SYNC inputs and dedicated test-mode architecture of MC88915TFN70 | Choose ICS557GI-70LF for new 3.3V designs needing smaller footprint or EMI reduction; retain MC88915TFN70 for legacy 5V PLCC-based repair or upgrade. |
Compared with MC88915TFN55, the MC88915TFN70 offers higher 2X_Q frequency headroom (70 MHz) and commercial-temp operation optimized for PC workloads; compared with ICS557GI-70LF, it provides superior testability via dual SYNC and PLL_EN but requires 5V-only supply and larger PLCC packaging.
Availability
MC88915TFN70 is available at Aetrix Electronics and suitable for desktop PC motherboard design, workstation multi-processor synchronization, and legacy industrial control backplane upgrades requiring stable component supply and long-lifecycle support.
Supply support for MC88915TFN70 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 systems in the 1990s, emphasizing low skew, PLL stability, and testability.
The MC88915T product line was engineered specifically for synchronous clock fanout in 5V x86 and RISC-based PC/workstation platforms, addressing skew-critical timing between CPU, memory, and I/O controllers.
FAQ
What is the maximum guaranteed 2X_Q output frequency for MC88915TFN70?
The MC88915TFN70 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 specification is validated across 0°C to +70°C ambient temperature and 5.0 V ±5% supply voltage, and defines the upper limit for system clock synthesis when using the frequency-doubled output.
Does MC88915TFN70 support 3.3V operation?
No, MC88915TFN70 is a 5V-only device specified for VCC = 5.0 V ±5%. It is not rated for 3.3V operation. For 3.3V-compatible clock drivers in the same functional family, Motorola published the MC88LV915T - a separate part number with different voltage ratings, drive strength, and AC characteristics.
How does the FREQ_SEL pin affect MC88915TFN70 operation?
The FREQ_SEL pin selects the feedback division ratio inside the MC88915TFN70's PLL: high = ÷1, low = ÷2. This allows the VCO to remain within its optimal 20–70 MHz operating range even when driven by low-frequency SYNC inputs - for example, holding FREQ_SEL low enables stable lock with a 10 MHz reference to generate 35 MHz Q outputs.
Can MC88915TFN70 be used in test-mode without a PLL reference clock?
Yes. When PLL_EN is pulled low, the MC88915TFN70 enters static test mode where the VCO is disabled and the device accepts arbitrary low-frequency clocks on either SYNC0 or SYNC1. In this mode, outputs remain functional (subject to OE/RST control), enabling board-level functional testing without requiring a stable PLL reference.
What is the purpose of the LOCK output on MC88915TFN70?
The LOCK output on MC88915TFN70 is an open-drain status signal that goes high within 10 ms of achieving steady-state phase and frequency lock after power-up and SYNC signal application. It goes low whenever phase lock is lost or PLL_EN is asserted low - providing real-time hardware verification of PLL health for system monitoring or fault detection circuits.
MC88915TFN70 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)
MC88915TFN70 FAQ
1.How can I place an order for MC88915TFN70 through Aetrix?
Please submit a Request for Quotation (RFQ) for MC88915TFN70 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 MC88915TFN70 reliable?
The price and inventory of MC88915TFN70 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC88915TFN70 is usually 5 days.
3.What payment methods are accepted for MC88915TFN70?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC88915TFN70 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC88915TFN70?
MC88915TFN70 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC88915TFN70 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 MC88915TFN70?
For technical support, including MC88915TFN70 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC88915TFN70 requirements.
6.How does Aetrix verify that MC88915TFN70 is sourced from the original manufacturer or authorized distributors?
All MC88915TFN70 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 MC88915TFN70 meets industry standards.
7.What is the process for return or replacement of MC88915TFN70?
All MC88915TFN70 units undergo pre-shipment inspection (PSI). If there is an issue with MC88915TFN70, 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 MC88915TFN70 part is unused and in its original packaging.
Return procedure for MC88915TFN70:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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