MC100H640

The MC10H/100H640 generates the necessary clocks for the 68030, 68040 and similar microprocessors. It is guaranteed to meet the clock specifications required by the 68030 and 68040 in terms of parttopart skew, withinpart skew and also duty cycle skew.

The user has a choice of using either TTL or PECL (ECL referenced to +5.0V) for the input clock. TTL clocks are typically used in present MPU systems. However, as clock speeds increase to 50MHz and beyond, the inherent superiority of ECL (particularly differential ECL) as a means of clock signal distribution becomes increasingly evident. The H640 also uses differential PECL internally to achieve its superior skew characteristic.

The H640 includes dividebytwo and dividebyfour stages, both to achieve the necessary duty cycle skew and to generate MPU clocks as required. A typical 50MHz processor application would use an input clock running at 100MHz, thus obtaining output clocks at 50MHz and 25MHz (see Logic Symbol).

The 10H version is compatible with MECL 10H^TM ECL logic levels, while the 100H version is compatible with 100K levels (referenced to +5.0V).
• Generates Clocks for 68030/040
• Meets 030/040 Skew Requirements
• TTL or PECL Input Clock
• Extra TTL and PECL Power/Ground Pins
• Asynchronous Reset
• Single +5.0V Supply