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Operating frequency: 125 MHz to 500 MHz
Supports DDRII SDRAM
Ten differential outputs from one differential input
Spread-Spectrum-compatible
Low jitter (cycle-to-cycle): < 40 ps
Very low skew: < 40 ps
Power management control input
1.8V operation
Fully JEDEC-jompliant
52-ball BGA and a 40-pin MLF (QFN)
Functional Description
The CY2SSTU877 is a high-performance, low-skew, low-jitter
zero delay buffer designed to distribute differential clocks in
high-speed applications. The CY2SSTU877 generates ten
differential pair clock outputs from one differential pair clock
input. In addition, the CY2SSTU877 features differential
feedback clock outputs and inputs. This allows the
CY2SSTU877 to be used as a zero-delay buffer. When used
as a zero-delay buffer in nested clock trees, the CY2SSTU877
locks onto the input reference and translates with near zero
delay to low-skew outputs.
This phase-locked loop (PLL) clock buffer is designed for a
VDD of 1.8V, an AVDD of 1.8 V and differential data input and
output levels. Package options include a plastic 526-ball
VFBGA and a 40-pin MLF(QFN). The device is a zero delay
buffer that distributes a differential clock input pair (CK, CK#)
to ten differential pair of clock outputs (Y[0:9], Y#[0:9]) and one
differential pair feedback clock outputs (FBOUT, FBOUT#).
The input clocks (CK, CK#), the feedback clocks (FBIN,
FBIN#), the LVCMOS (OE, OS), and the analog power input
(AVDD) control the clock outputs.
The PLL in the CY2SSTU877 clock driver uses the input
clocks (CK, CK#) and the feedback clocks (FBIN, FBIN#) to
provide high-performance, low-skew, low-jitter output differ-
ential clocks (Y[0:9], Y#[0:9]). The CY2SSTU877 is also able
to track Spread Spectrum Clocking (SSC) for reduced EMI.
When AVDD is grounded, the PLL is turned off and bypassed
for test purposes. When both clock signals (CK, CK#) are logic
low, the device will enter a low power mode. An input logic
detection circuit on the differential inputs, independent from
the input buffers, will detect the logic low level and perform a
low power state where all outputs, the feedback and the PLL
are OFF. When the inputs transition from both being logic low
to being differential signals, the PLL will be turned back on, the
inputs and outputs will be enabled and the PLL will obtain
phase lock between the feedback clock pair (FBIN, FBIN#)
and the input clock pair (CK, CK#) within the specified stabili-
zation time tL.
Cypress Semiconductor Corporation
Document #: 38-07575 Rev. **
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3901 North First Street
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San Jose
,
CA 95134
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408-943-2600
Revised August 21,2003
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