CDC913 PC MOTHERBOARD CLOCK GENERATOR WITH DUAL 1-TO-4 BUFFERS AND 3-STATE OUTPUTS

SCAS502C - APRIL 1995 - REVISED MAY 1996

features

Generates Programmable CPU Clock Output (50 MHz, 60 MHz, or 66 MHz)
Generates 33-MHz Clock for Asynchronous PCI
One 14.318-MHz Reference Clock Output
All Output Clock Frequencies Derived From a Single 14.31818-MHz Crystal Input
LVTTL-Compatible Inputs and Outputs
Internal Loop Filters for Phase-Lock Loops Eliminate the Need for External Components
Operates at 3.3-V V_CC
Package Options Include Plastic Small-Outline (DW) and Shrink Small-Outline (DB) Packages

description

The CDC913 is a high-performance clock generator with integrateddual 1-to-4 buffers, which simplifies clock system design for PCmotherboards. The CDC913 consists of a crystal oscillator, twophase-locked loops (PLL), and two 1-to-4 buffers. The CDC913generates all frequencies using a single 14.318-MHz crystal.

The CPUCLK output is programmable to one of three frequencies (50MHz, 60 MHz, or 66 MHz) via the SEL0 and SEL1 inputs. PCICLK outputsa 33-MHz clock, independent of the CPUCLK frequency. REFCLK providesa buffered copy of the 14.318-MHz reference. The oscillator and PLLsin the CDC913 are bypassed when in the TEST mode, i.e., SEL1 = SEL0 =H. When in the TEST mode, a test clock can be driven over the X1input and buffered out from the PCICLK, CPUCLK, and REFCLK outputs.

Outputs 1Yn and 2Yn are 3-state outputs and are enabled via . When is high, the outputs are in thehigh-impedance state. When islow, the outputs are enabled.

Since the CDC913 is based on PLL circuitry, it requires astabilization time to achieve phase lock of the PLL. Thisstabilization time is required following power up and application ofa fixed-frequency, fixed-phase signal at the X1 input, and followingany changes to the SELn inputs.

Title: PC MOTHERBOARD CLOCK GENERATOR WITH DUAL 1-TO-4 BUFFERS AND 3-STATE OUTPUTS
Product Family: OTHER DIGITAL LOGIC
Device Functionality: CLOCK GENERATOR/BUFFER
Orderable Devices: CDC913DW

View the complete PDF datasheet: scas502c.pdf (126 K Bytes) (Requires Acrobat Reader 3.x)

View more information about generic part numbers:CDC913

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