FEATURES
· Spread-Spectrum Clock Compatible
· Operating Frequency: 60 MHz to 220 MHz
· Low Jitter (Cycle-Cycle): ±60 ps (±40 ps at 200
MHz)
· Low Static Phase Offset: ±50 ps
· Low Jitter (Period): ±60 ps (±30 ps at 200 MHz)
· 1-to-4 Differential Clock Distribution (SSTL2)
· Best in Class for VOX = VDD/2 ±0.1 V
· Operates From Dual 2.6-V or 2.5-V Supplies
· Available in a 28-Pin TSSOP Package
· Consumes < 100-mA Quiescent Current
· External Feedback Pins (FBIN, FBIN) Are Used
to Synchronize the Outputs to the Input
Clocks
· Meets/Exceeds JEDEC Standard (JESD82-1)
For DDRI-200/266/333 Specification
· Meets/Exceeds Proposed DDRI-400
Specification (JESD82-1A)
· Enters Low-Power Mode When No CLK Input
Signal Is Applied or PWRDWN Is Low

APPLICATIONS
· DDR Memory Modules (DDR400/333/266/200)
· Zero-Delay Fan-Out Buffer

DESCRIPTION
The CDCVF855 is a high-performance, low-skew,
low-jitter, zero-delay buffer that distributes a
differential clock input pair (CLK, CLK) to 4
differential pairs of clock outputs (Y[0:3], Y[0:3]) and one differential pair of feedback clock outputs
(FBOUT, FBOUT). The clock outputs are controlled
by the clock inputs (CLK, CLK), the feedback clocks
(FBIN, FBIN), and the analog power input (AVDD).
When PWRDWN is high, the outputs switch in phase
and frequency with CLK. When PWRDWN is low, all
outputs are disabled to a high-impedance state
(3-state) and the PLL is shut down (low-power
mode). The device also enters this low-power mode
when the input frequency falls below a suggested
detection frequency that is below 20 MHz (typical 10
MHz). An input frequency-detection circuit detects
the low-frequency condition and, after applying a
>20-MHz input signal, this detection circuit turns the
PLL on and enables the outputs.
When AVDD is strapped low, the PLL is turned off
and bypassed for test purposes. The CDCVF855 is
also able to track spread-spectrum clocking for
reduced EMI.
Because the CDCVF855 is based on PLL circuitry, it
requires a stabilization time to achieve phase-lock of
the PLL. This stabilization time is required following
power up. The CDCVF855 is characterized for both
commercial and industrial temperature ranges.