CY28346-2
Table 7. Host Clock (HCSL) Buffer Characteristics
Characteristic
Minimum
Maximum
Ro
3000 Ohms (recommended)
N/A
Ros
Vout
N/A
1.2V
Table 8. CPU Clock Current Select Function
Mult0
Board Target Trace/Term Z
50 Ohms
Reference R, Iref – Vdd (3*Rr)
Rr = 221 1%, Iref = 5.00 mA
Rr = 475 1%, Iref = 2.32 mA
Output Current
Ioh = 4*Iref
Voh @ Z
1.0V @ 50
0.7V @ 50
0
1
50 Ohms
Ioh = 6*Iref
Table 9. Group Timing Relationship and Tolerances
Description
Offset
2.5 ns
0.0 ns
2.5 ns
Tolerance
r1.0 ns
Conditions
3V66 to PCI
3V66 Leads PCI (unbuffered mode)
0 degrees phase shift
48M_USB to 48M_DOT Skew
66B to PCI offset
r1.0 ns
r1.0 ns
66B leads PCI (buffered mode)
Table 10.Maximum Lumped Capacitive Output Loads
66IN to 66B Buffered Prop Delay
Clock
PCI Clocks
Max Load
Unit
pF
pF
pF
pF
pF
pF
The 66IN to 66B(0:2) output delay is shown in Figure 11.
30
30
30
20
10
50
The Tpd is the prop delay from the input pin (66IN) to the
output pins (66B[0:2]). The outputs’ variation of Tpd is
described in the AC parameters section of this data sheet. The
measurement is taken at 1.5V.
3V66
66B
48M_USB Clock
48M_DOT
REF Clock
66B to PCI Buffered Clock Skew
Figure 12 shows the difference (skew) between the 3V33(0:5)
outputs when the 66M clocks are connected to 66IN. This
offset is described in the Group Timing Relationship and Toler-
ances section of this data sheet. The measurements were
taken at 1.5V.
USB and DOT 48M Phase Relationship
The 48M_USB and 48M_DOT clocks are in phase. It is under-
stood that the difference in edge rate will introduce some in
inherent offset. When 3V66_1/VCH clock is configured for
VCH (48-MHz) operation it is also in phase with the USB and
DOT outputs. See Figure 10.
3V66 to PCI Unbuffered Clock Skew
Figure 13 shows the timing relationship between 3V66(0:5)
and PCI(0:6) and PCIF when configured to run in the unbuf-
fered mode.
48MUSB
48MDOT
Figure 10. 48M_USB and 48M_DOT Phase Relationship
66IN
66B
Tpd
Figure 11. 66IN to 66B(0:2) Output Delay Figure
Rev 1.0,November 20, 2006
Page 12 of 19
SPECTRALINEAR [ SPECTRALINEAR INC ]
