MC100H642FNG

Overview

The MC100H642FNG is a clock driver and distribution IC designed for 68030/68040 microprocessors. It accepts ECL or TTL inputs and provides eight differential TTL outputs with a maximum frequency of 100 MHz. The device operates on a single +5.0 V supply (4.75V to 5.25V) within an operating temperature range of 0°C to 85°C. Packaged in a PLCC-28 surface-mount format, it includes internal divide-by-two and divide-by-four stages to generate required MPU clocks while maintaining strict part-to-part and within-part skew specifications.

Feature Summary

• Generates necessary clocks for 68030/68040 MPUs with guaranteed skew performance
• Accepts either TTL or PECL (ECL referenced to +5.0 V) input sources
• Includes asynchronous reset and extra power/ground pins for stability
• Single +5.0 V supply operation with integrated divide-by-two and four stages

Applications

• Clock generation for Motorola 68030 microprocessors
• Clock generation for Motorola 68040 microprocessors
• High-speed clock distribution systems requiring low skew

Procurement Notes

Verify the component status as discontinued by checking official manufacturer records. Confirm that the PLCC-28 package dimensions match the target PCB footprint. Ensure the design supports the specific voltage levels and current requirements outlined in the datasheet before procurement.

Selection Notes

Select this component when designing for 68030 or 68040 MPU architectures requiring precise clock synchronization. Verify compatibility between the chosen input source (TTL vs. PECL) and the system's existing clock generator. Ensure the application environment remains within the specified 0°C to 85°C operating temperature range.

Part Context

This device belongs to the MC10H/100H642 series, which are specialized clock drivers. The '100' prefix indicates compatibility with 100K logic levels referenced to +5.0 V, distinguishing it from the standard MECL 10H compatible version. It serves as a critical interface for distributing synchronized clock signals to high-performance processors.

Replacement Considerations

Public confirmed substitute part numbers are not available in the provided documentation. As the product is listed as discontinued, consult the manufacturer for potential obsolescence management options or alternative family members if direct pin-compatible replacements are required.

FAQ

What is the function of the Select (SEL) pin?

The SEL pin determines the active input source. A LOW signal selects the ECL input (DE/DE), while a HIGH signal selects the TTL input (DT).

How does the device handle duty cycle control?

The H642 uses internal differential PECL circuitry to achieve superior skew characteristics. To maintain a duty cycle of ±5% at 50 MHz, load capacitance and power supply variation must be limited according to the datasheet graphs.

What happens to the outputs during an asynchronous reset?

A LOW signal on the Reset (R) pin forces all Q outputs LOW. The device also features a reset recovery time specification to ensure stable output states after the reset pulse ends.