CDCV857A Datasheet, PDF (1/14 Pages) Texas Instruments – 2.5-V PHASE LOCK LOOP CLOCK DRIVER

CDCV857A
2.5-V PHASE LOCK LOOP CLOCK DRIVER
D Phase-Lock Loop Clock Driver for Double
Data-Rate Synchronous DRAM
Applications
D Spread Spectrum Clock Compatible
D Operating Frequency: 60 to 180 MHz
D Low Jitter (cyc–cyc): ±50 ps
D Distributes One Differential Clock Input to
Ten Differential Outputs
SCAS667A – APRIL 2001 – REVISED AUGUST 2002
D Three-State Outputs When the Input
Differential Clocks Are <20 MHz
D Operates From Dual 2.5-V Supplies
D Available in a 48-Pin TSSOP Package or
56-Ball MicroStar Junior BGA Package
D Consumes < 200-µA Quiescent Current
D External Feedback PIN (FBIN, FBIN) Are
Used to Synchronize the Outputs to the
Input Clocks
description
The CDCV857A is a high-performance, low-skew, low-jitter zero delay buffer that distributes a differential clock
input pair (CLK, CLK) to ten differential pairs of clock outputs (Y[0:9], Y[0:9]) and one differential pair of feedback
clock output (FBOUT, FBOUT). The clock outputs are controlled by the clock inputs (CLK, CLK), the feedback
clocks (FBIN, FBIN), and the analog power input (AV_DD). When PWRDWN is high, the outputs switch in phase
and frequency with CLK. When PWRDWN is low, all outputs are disabled to 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 will detect the low frequency condition and after applying a >20 MHz input signal this
detection circuit turns on the PLL again and enables the outputs.
When AV_DD is strapped low, the PLL is turned off and bypassed for test purposes. The CDCV857A is also able
to track spread spectrum clocking for reduced EMI.
Since the CDCV857A 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 CDCV857A is characterized for operation from 0°C
to 85°C.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
MicroStar Junior is a trademark of Texas Instruments Incorporated.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
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Copyright  2002, Texas Instruments Incorporated
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