VSC8601 Datasheet
Electrical Specifications
5.3.1
Reference Clock Input
The following table lists the specifications for the reference clock input frequency
including various frequencies, duty cycle, and accuracy.
Table 68.
AC Characteristics for REFCLK Input
Parameter
Symbol Minimum Typical Maximum Unit
Frequency with 25 MHz input
Frequency with 125 MHz input
Frequency accuracy
fCLK25
fCLK125
fTOL
25
MHz
MHz
ppm
%
125
50
60
4
Duty cycle
%
40
DUTY
Rise time with 25 MHz input (20% to 80%)
tR25
ns
Rise time with 125 MHz input (20% to
80%)
tR125
1
ns
When using the 25 MHz crystal clock input option, the additional specifications in the
following table are required.
Table 69.
AC Characteristics for REFCLK Input with 25 MHz Clock Input
Parameter
Minimum
Typical
Maximum Unit
Crystal parallel load capacitance
Crystal equivalent series resistance
18
20
30
pF
10
Ω
5.3.2
Clock Output
The specifications in the following table show the AC characteristics for the clock output
of the VSC8601 device.
Table 70.
AC Characteristics for the CLKOUT Pin
Parameter
Symbol Minimum
Typical Maximum Unit Condition
CLKOUT frequency
fCLK
125.00
MHz 125 MHz output
clock
CLKOUT cycle time
tCYC
8.0
ns
125 MHz output
clock
Frequency stability
Duty cycle
fSTABILITY
50
56
1
ppm
%
%
44
50
DUTY
Clock rise and fall
tR and tF
ns
times (20% to 80%)
Total jitter
JCLK
217
600
ps
Measured
peak-to-peak,
time interval
error
Revision 4.1
September 2009
Page 76
VITESSE [ VITESSE SEMICONDUCTOR CORPORATION ]
