FEATURES
· 1.8-V Phase Lock Loop Clock Driver for
Double Data Rate (DDR II) Applications
· Spread Spectrum Clock Compatible
· Operating Frequency: 10 MHz to 400 MHz
· Low Current Consumption: <135 mA
· Low Jitter (Cycle-Cycle): ±30 ps
· Low Output Skew: 35 ps
· Low Period Jitter: ±20 ps
· Low Dynamic Phase Offset: ±15 ps
· Low Static Phase Offset: ±50 ps
· Distributes One Differential Clock Input to Ten
Differential Outputs
· 52-Ball μBGA (MicroStar™ Junior BGA,
0,65-mm pitch) and 40-Pin MLF
· External Feedback Pins (FBIN, FBIN) are Used
to Synchronize the Outputs to the Input
Clocks
· Meets or Exceeds JESD82-8 PLL Standard for
PC2-3200/4300
· Fail-Safe Inputs

DESCRIPTION
The CDCU877 is a high-performance, low-jitter, low-skew, zero-delay buffer that distributes a differential clock
input pair (CK, CK) to ten differential pairs of clock outputs (Yn, Yn) and to one differential pair of feedback clock
outputs (FBOUT, FBOUT). The clock outputs are controlled by the input clocks (CK, CK), the feedback clocks
(FBIN, FBIN), the LVCMOS control pins (OE, OS), and the analog power input (AVDD). When OE is low, the
clock outputs, except FBOUT/FBOUT, are disabled while the internal PLL continues to maintain its locked-in
frequency. OS (output select) is a program pin that must be tied to GND or VDD. When OS is high, OE functions
as previously described. When OS and OE are both low, OE has no affect on Y7/Y7, they are free running.
When AVDD is grounded, the PLL is turned off and bypassed for test purposes.
When both clock inputs (CK, CK) are logic low, the device enters in a low power mode. An input logic detection
circuit on the differential inputs, independent from input buffers, detects the logic low level and performs in a low
power state where all outputs, the feedback, and the PLL are off. When the clock inputs transition from being
logic low to being differential signals, the PLL turns back on, the inputs and the outputs are enabled, and the
PLL obtains phase lock between the feedback clock pair (FBIN, FBIN) and the clock input pair (CK, CK) within
the specified stabilization time.
The CDCU877 is able to track spread spectrum clocking (SSC) for reduced EMI. This device operates from
—40°C to 85°C.