XRK69772 Datasheet, PDF (1/12 Pages) Exar Corporation – 1:12 LVCMOS PLL CLOCK GENERATOR

PRELIMINARY
XRK69772
1:12 LVCMOS PLL CLOCK GENERATOR
APRIL 2006
REV. P1.0.0
GENERAL DESCRIPTION
The XRK69772 is a PLL based LVCMOS Clock Generator
targeted for high performance and low skew clock distribu-
tion applications. The XRK69772 can select between one
of three reference inputs and provides 14 LVCMOS outputs
-12 outputs (3 banks of 4) for clock distribution, 1 for feed-
back and 1 for synchronization.
The XRK69772 is a highly flexible device. It can be config-
ured to accept either a crystal oscillator input or one of two
LVCMOS compatible inputs for use as the input reference
clock source. To support clock redundancy, two LVCMOS
inputs are provided. Switching the internal reference clock
is controlled by the control input, CLK_SEL.
The XRK69772 uses PLL technology to frequency lock its
outputs to the input reference clock. The divider in the feed-
back path will determine the frequency of the VCO. Each of
the separate output banks can individually divide down the
VCO output frequency. This allows the XRK69772 to gen-
erate a multitude of different bank frequency ratios and out-
put-to-input frequency ratios.
The outputs of the XRK69772 can individually be immobi-
lized, in the low state, by use of the stop clock feature. All
outputs except QC0 and QFB can be immobilized through a
2 pin serial interface. Global output disabling and reset can
be achieved the control input MR/OE.
The XRK69772 also has a QSYNC output which can be
used for system synchronization purposes. It monitors
Bank A and Bank C outputs and goes low one period of the
faster clock prior to coincident rising edges of Bank A and
Bank C clocks. QSYNC then goes high again when the
coincident rising edges of Bank A and Bank C occur. This
feature is used primarily in applications where Bank A and
Bank C are running at different frequencies, and is
particularly useful when they are running at non-integer
multiples of one another.
The XRK69772 has an output frequency range of 8.33MHz
to125MHz and an input frequency range of 5MHz to
120MHz.
FEATURES
• Fully Integrated PLL
• Selectable crystal oscillator or LVCMOS inputs for
reference clock source
• 14 LVCMOS outputs
■ 3 banks with 4 outputs each. Frequencies can
be individually controlled by bank
■ 1 dedicated feedback with frequency control
■ 1 Sync
• VCO Range 200MHz to 480MHz
• Output freq. range: 5MHz to 240MHz
• Max Output Skew of 250ps
• Cycle-to-cycle jitter: 150ps (typ)
APPLICATIONS
• System Clock generator
• Zero Delay Buffer
PRODUCT NUMBER
XRK69772CR
XRK69772IR
PRODUCT ORDERING INFORMATION
PACKAGE TYPE
OPERATING TEMPERATURE RANGE
52-LEAD LQFP
0°C to +70°C
52-LEAD LQFP
-40°C to +85°C
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • [phone] • FAX [phone] • www.exar.com