CY28346 Cypress Semiconductor, CY28346 Datasheet - Page 8

• Manufacturer Part Number: CY28346
• Description: Clock Synthesizer with Differential CPU Outputs
• Manufacturer: Cypress Semiconductor

Document #: 38-07331 Rev. *B
Iout is selectable depending on implementation. The param-
eters above apply to all configurations. Vout is the voltage at
the pin of the device.
Table 5. CPU Clock Current Select Function
Table 6. Group Timing Relationship and Tolerances
USB and DOT 48M Phase Relationship
The 48MUSB and 48MDOT clocks are in phase. It is under-
stood that the difference in edge rate will introduce some
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 5.
66IN to 66B(0:2) Buffered Prop Delay
The 66IN to 66B(0:2) output delay is shown in Figure 6.
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 taken at 1.5V.
3V66 to PCI
48MUSB to 48MDOT Skew
66B(0:2) to PCI offset
Mult0
PCIF(0:2)
66B(0:2)
0
1
PCI(0:6)
66B(0:2)
66IN
48MUSB
48MDOT
Description
Board Target Trace/Term Z
Tpd
3.5ns
1.5-
Figure 7. Buffer Mode – 33V66(0:1); 66BUF(0:2) Phase Relationship
50
50
Figure 5. 48MUSB and 48MDOT Phase Relationship
Figure 6. 66IN to 66B(0:2) Output Delay Figure
Offset
2.5 ns
0.0 ns
2.5 ns
Reference R, Iref – Vdd (3*Rr)
Rr = 221 1%, Iref = 5.00mA
Rr = 475 1%, Iref = 2.32mA
Tolerance
The various output current configurations are shown in the
host swing select functions table. For all configurations, the
deviation from the expected output current is ±7% as shown in
the current accuracy table.
66B(0:2) to PCI Buffered Clock Skew
Figure 7 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.
3V66 to PCI Un-Buffered Clock Skew
Figure 8 shows the timing relationship between 3V66(0:5) and
PCI(0:6) and PCI_F(0:2) when configured to run in the unbuf-
fered mode.
1.0 ns
1.0 ns
1.0 ns
3V66 Leads PCI (unbuffered mode)
0 degrees phase shift
66B Leads PCI (buffered mode)
Output Current
Ioh = 4*Iref
Ioh = 6*Iref
Conditions
CY28346
1.0V @ 50
0.7V @ 50
Page 8 of 20
Voh @ Z