LCK4953 Datasheet, PDF (1/6 Pages) Agere Systems – Low-Voltage PLL Clock Driver

Data Sheet
November 2001
LCK4953
Low-Voltage PLL Clock Driver
Features
• Fully integrated PLL
• Output frequency up to 130 MHz in PLL mode
• Nine outputs with high-impedance disable
• 32-lead TQFP
• 50 ps cycle-to-cycle jitter
• Pin compatible with the Motorola^® MPC953 clock
driver
Description
The LCK4953 is a PLL-based clock driver device
intended for high-performance clock tree designs.
The LCK4953 is 3.3 V compatible with output
frequencies of up to 130 MHz and output skews of
75 ps. The LCK4953 can meet the most demanding
timing requirements and employs on-chip voltage
regulators to minimize cycle-to-cycle jitter and phase
jitter.
The LCK4953 is ideal for use as a zero delay, low
skew, fan-out buffer due to its differential LVPECL
reference input along with an external feedback
input. The MROEB pin of the LCK4953, when driven
high, will reset the internal counters and 3-state the
output buffers. The LCK4953 has been optimized for
zero delay performance.
The LCK4953 is fully 3.3 V compatible and requires
no external loop filter components. All control inputs
accept LVCMOS or LVTTL compatible levels while
the outputs provide LVCMOS levels with the ability to
drive terminated 50 Ω transmission lines. For series-
terminated 50 Ω lines, each of the LCK4953 outputs
can drive two traces giving the device an effective
fan-out of 1:18. For the optimum combination of
board density and performance, the device is
packaged in a 7 mm × 7 mm 32-lead TQFP package.
Table 1. Function Table
BYPASSB
1
0
MROEB
1
0
VCOSEL
1
0
PLLEN
1
0
Function
PLL Enabled
PLL Bypass
Function
Outputs Disabled
Outputs Enabled
Function
÷8
÷4
Function
Select VCO
Select PELCLK