CY28410 Cypress Semiconductor, CY28410 Datasheet - Page 7

• Manufacturer Part Number: CY28410
• Description: Clock Generator for Intel Grantsdale Chipset
• Manufacturer: Cypress Semiconductor

Document #: 38-07593 Rev. *C
Byte 6: Control Register 6 (continued)
Byte 7: Vendor ID
Crystal Recommendations
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.
Table 5. Crystal Recommendations
14.31818 MHz
Frequency
Bit
Bit
1
2
0
7
6
5
4
3
2
1
0
(Fund)
Externally
Externally
Externally
selected
selected
selected
@Pup
@Pup
0
0
1
0
1
0
0
0
Cut
AT
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
Loading Load Cap
Parallel
CPUT/C
CPUT/C
CPUT/C
Name
Name
20 pF
0.1 mW
(max.)
Drive
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
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
Shunt Cap
(max.)
Crystal 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.
5 pF
Motional
0.016 pF
(max.)
Description
Description
Tolerance
35 ppm
(max.)
Stability
30 ppm
(max.)
CY28410
Page 7 of 18
(max.)
Aging
5 ppm