CY28447
Byte 12: Control Register 12
Bit
@Pup
Name
CLKREQ#9
Description
7
6
5
4
3
2
1
0
0
CLKREQ#9 Input Enable
0 = Disable 1 = Enable
0
0
0
0
0
0
0
CLKREQ#8
CLKREQ#7
CLKREQ#6
CLKREQ#5
CLKREQ#4
CLKREQ#3
CLKREQ#2
CLKREQ#8 Input Enable
0 = Disable 1 = Enable
CLKREQ#7 Input Enable
0 = Disable 1 = Enable
CLKREQ#6 Input Enable
0 = Disable 1 = Enable
CLKREQ#5 Input Enable
0 = Disable 1 = Enable
CLKREQ#4 Input Enable
0 = Disable 1 = Enable
CLKREQ#3 Input Enable
0 = Disable 1 = Enable
CLKREQ#2 Input Enable
0 = Disable 1 = Enable
Byte 13: Control Register 13
Bit
@Pup
Name
Description
7
6
0
CLKREQ#1
CLKREQ#1 Input Enable
0 = Disable 1 = Enable
1
LCD 96_100M Clock
Speed
LCD 96_100M Clock Speed
0 = 96 MHz 1 = 100 MHz
5
4
3
1
1
1
RESERVED
RESERVED
PCI4
RESERVED, Set = 1
RESERVED, Set = 1
PCI4 (Spread and Non-spread) Output Drive Strength
0 = Low, 1 = High
2
1
0
1
1
1
PCI3
PCI2
PCI1
PCI3 (Spread and Non-spread) Output Drive Strength
0 = Low, 1 = High
PCI2 (Spread and Non-spread) Output Drive Strength
0 = Low, 1 = High
PCI1 (Spread and Non-spread) Output Drive Strength
0 = Low, 1 = High
Table 5. Crystal Recommendations
Frequency
Drive
(max.)
Shunt Cap Motional
(max.)
Tolerance
(max.)
Stability
(max.)
Aging
(max.)
(Fund)
Cut
Loading Load Cap
(max.)
14.31818 MHz
AT
Parallel 20 pF
0.1 mW
5 pF
0.016 pF
35 ppm
30 ppm
5 ppm
The CY28447 requires a Parallel Resonance Crystal. Substi-
tuting a series resonance crystal will cause the CY28447 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.
the crystal will see must be considered to calculate the appro-
priate capacitive loading (CL).
Figure 1 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.
Crystal Loading
Crystal loading plays a critical role in achieving low ppm perfor-
mance. To realize low ppm performance, the total capacitance
Rev 1.0,November 20, 2006
Page 9 of 21
SPECTRALINEAR [ SPECTRALINEAR INC ]
