CY28435OXCT SPECTRALINEAR [SpectraLinear Inc], CY28435OXCT Datasheet - Page 10

• Manufacturer Part Number: CY28435OXCT
• Description: Clock Generator for Intel Grantsdale Chipset
• Manufacturer: SPECTRALINEAR [SpectraLinear Inc]

Rev 1.0, November 20, 2006
Byte 14: Control Register 14 (continued)
Byte 15: Control Register 15
Byte 16: Control Register 16
Crystal Recommendations
The CY28435 requires a Parallel Resonance Crystal. Substi-
tuting a series resonance crystal will cause the CY28435 to
operate at the wrong frequency and violate the ppm specifi-
cation. For most applications there is a 300-ppm frequency
shift between series and parallel crystals due to incorrect
loading.
Table 4. Crystal Recommendations
14.31818 MHz
Frequency
Bit
Bit
Bit
1
0
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
(Fund)
@Pup
@Pup
@Pup
1
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
1
Cut
AT
Watchdog Autorecovery Watchdog Autorecovery Mode
Loading Load Cap
Parallel
SRC_FREQ_SEL
Prog_SRC_EN
Prog_CPU_EN
Recovery_N8
Recovery N7
Recovery N6
Recovery N5
Recovery N4
Recovery N3
Recovery N2
Recovery N1
Recovery N0
RESERVED
SRC_SATA
USB48_1
Name
Name
Name
REF1
PCIF
20 pF
0.1 mW
Free running 33-MHz Output Drive Strength
0 = 2x, 1 = 1x
Watchdog Recovery Bit
Watchdog Recovery Bit
Watchdog Recovery Bit
Watchdog Recovery Bit
Watchdog Recovery Bit
Watchdog Recovery Bit
Watchdog Recovery Bit
Watchdog Recovery Bit
Watchdog Recovery Bit
REF1 Output Enable
0 = Disable, 1 = Enable
USB48_1 Output Enable
0 = Disable, 1 = Enable
SRC Frequency selection
0: SRC frequency is selected via the FSE pin
1: SRC frequency is initially set to 167 MHz.
RESERVED, Set = 0
SATA PLL Spread Spectrum Enable
0 = Spread off, 1 = Spread on
Programmable SRC frequency enable
0 = disabled, 1 = enabled.
Programmable CPU frequency enable
0 = disabled, 1 = enabled.
0 = Disable (Manual), 1= Enable (Auto)
(max.)
Drive
Shunt Cap
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).
Figure 2 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.
(max.)
5 pF
Motional
0.016 pF
(max.)
Description
Description
Description
Tolerance
35 ppm
(max.)
Stability
30 ppm
(max.)
CY28435
Page 10 of 22
(max.)
Aging
5 ppm