C5001 Datasheet, PDF (6/13 Pages) List of Unclassifed Manufacturers – Low Skew Multiple Frequency PCI Clock Generator with EMI Reducing SSCG.

C5001
Low Skew Multiple Frequency PCI Clock Generator with EMI Reducing SSCG.
Approved Product
Clock Enable Functions and Timing
Each output clock may be either disabled or enabled by either setting or clearing its respective I²C register control bit.
All clocks are stopped in the low state. All clocks maintain a valid high period before transitioning from running to
stopped. The clocks transition between running and stopped occurs immediately after the I²C register bit is cleared and
the clock transitions to a low state. See figure below.
Internal
Clock
I²C
Register
BIT
2 Output
1 Output
A
B
A: represents one output ÷2 clock cycle (one 33.3 MHz cycle period).
B: represents one output clock ÷ 1 cycle (one 66.6 MHz cycle period)..
Output Frequency Change Relationships
The I²C registers are initially set (initialized) by the voltage levels present on the clocks output pins at power up.
Subsequently these bits may be changed via I²C commands.
Output clocks have the capability to be changed, on the fly, via the devices I²C register bits. If Synchronous switching is
required, it may be achieved by first disabling a specific clock, changing its frequency and then re-enabling it via the I²C
register control bits that are provided for these functions.
Synchronous switching is defines at the changing of the output frequency of a clock from one frequency to another in
such a manner as to not produce any clock cycles shorter than the higher of the 2 frequencies or longer than the period
of the lower of the 2 frequencies. The disable and enable I2C register bit control of each clock is logically implemented
to eliminate clock glitches when each clock is either enabled or enabled.
CAUTION: Switching clock frequencies without first disabling the clock may produce an output clock glitch
(short or stretched period clock) during frequency transition!
INTERNATIONAL MICROCIRCUITS, INC. 525 LOS COCHES ST.
MILPITAS, CA 95035. TEL: [phone]. FAX [phone]
Rev.2.1
6/14/1999
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