CY2305
CY2309
Low-Cost 3.3V Zero Delay Buffer
Cypress Semiconductor Corporation
•
198 Champion Court
•
San Jose
, CA 95134-1709
•
408-943-2600
Document #: 38-07140 Rev. *I
Revised September 18, 2008
Features
■ 10 MHz to 100-/133 MHz operating range, compatible with CPU
and PCI bus frequencies
■ Zero input-output propagation delay
■ 60 ps typical cycle-to-cycle jitter (high drive)
■ Multiple low-skew outputs
❐ 85 ps typical output-to-output skew
❐ One input drives five outputs (CY2305)
❐ One input drives nine outputs, grouped as 4 + 4 + 1 (CY2309)
■ Compatible with Pentium-based systems
■ Test Mode to bypass phase-locked loop (PLL) (CY2309 only
[see “Select Input Decoding” on page 3])
■ Available in space-saving 16-pin 150-mil SOIC or 4.4-mm
TSSOP packages (CY2309), and 8-pin, 150-mil SOIC package
(CY2305)
■ 3.3V operation
■ Industrial temperature available
Functional Description
The CY2309 is a low-cost 3.3V zero delay buffer designed to
distribute high-speed clocks and is available in a 16-pin SOIC or
TSSOP package. The CY2305 is an 8-pin version of the
CY2309. It accepts one reference input, and drives out five
low-skew clocks. The -1H versions of each device operate at up
to 100-/133 MHz frequencies, and have higher drive than the -1
devices. All parts have on-chip PLLs which lock to an input clock
on the REF pin. The PLL feedback is on-chip and is obtained
from the CLKOUT pad.
The CY2309 has two banks of four outputs each, which can be
controlled by the Select inputs as shown in the “Select Input
Decoding” table on page 3. If all output clocks are not required,
BankB can be three-stated. The select inputs also allow the input
clock to be directly applied to the outputs for chip and system
testing purposes.
The CY2305 and CY2309 PLLs enter a power down mode when
there are no rising edges on the REF input. In this state, the
outputs are three-stated and the PLL is turned off, resulting in
less than 25.0
μA current draw for these parts. The CY2309 PLL
shuts down in one additional case as shown in the table below.
Multiple CY2305 and CY2309 devices can accept the same input
clock and distribute it. In this case, the skew between the outputs
of two devices is guaranteed to be less than 700 ps.
The
CY2305/CY2309
is
available
in
two/three
different
configurations, as shown in the ordering information (page 10).
The CY2305-1/CY2309-1 is the base part. The CY2305-1H/
CY2309-1H is the high-drive version of the -1, and its rise and
fall times are much faster than the -1s.
Logic Block Diagram
PLL
MUX
Select Input
REF
S2
S1
CLKA1
CLKA2
CLKA3
CLKA4
CLKB1
CLKB2
CLKB3
CLKB4
Decoding
CLKOUT
