CY28410 Datasheet, PDF (7/17 Pages) Cypress Semiconductor – Clock Generator for Intel Grantsdale Chipset

CY28410
Byte 6: Control Register 6 (continued)
Bit
@Pup
2
Externally
selected
1
Externally
selected
0
Externally
selected
Name
CPUT/C
CPUT/C
CPUT/C
Description
FS_C. Reflects the value of the FS_C pin sampled on power-up
0 = FS_C was low during VTT_PWRGD# assertion
FS_B. Reflects the value of the FS_B pin sampled on power-up
0 = FS_B was low during VTT_PWRGD# assertion
FS_A. Reflects the value of the FS_A pin sampled on power-up
0 = FS_A was low during VTT_PWRGD# assertion
Byte 7: Vendor ID
Bit
@Pup
7
0
6
0
5
1
4
0
3
1
2
0
1
0
0
0
Name
Revision Code Bit 3
Revision Code Bit 2
Revision Code Bit 1
Revision Code Bit 0
Vendor ID Bit 3
Vendor ID Bit 2
Vendor ID Bit 1
Vendor ID Bit 0
Revision Code Bit 3
Revision Code Bit 2
Revision Code Bit 1
Revision Code Bit 0
Vendor ID Bit 3
Vendor ID Bit 2
Vendor ID Bit 1
Vendor ID Bit 0
Description
Crystal Recommendations
Crystal Loading
The CY28410 requires a Parallel Resonance Crystal. Substi-
tuting a series resonance crystal will cause the CY28410 to
operate at the wrong frequency and \violate the ppm specifi-
cation. For most applications there is a 300ppm frequency shift
between series and parallel crystals due to incorrect loading.
Crystal loading plays a critical role in achieving low ppm perfor-
mance. To realize low ppm performance, the total capacitance
the crystal will see must be considered to calculate the appro-
priate capacitive loading (CL).
The following diagram shows a typical crystal configuration
using the two trim capacitors. An important clarification for the
following discussion is that the trim capacitors are in series
with the crystal not parallel. It’s a common misconception that
load capacitors are in parallel with the crystal and should be
approximately equal to the load capacitance of the crystal.
This is not true.
Table 5. Crystal Recommendations
Frequency
(Fund)
14.31818 MHz
Cut
Loading Load Cap
Drive
(max.)
Shunt Cap Motional
(max.) (max.)
Tolerance
(max.)
Stability
(max.)
AT Parallel 20 pF 0.1 mW
5 pF
0.016 pF 35 ppm
30 ppm
Aging
(max.)
5 ppm
Rev 1.0, November 21, 2006
Page 7 of 17