CY24488
Document #: 001-09608 Rev. *A
Page 4 of 15
Programming Flow
The device registers may be programmed in any sequence,
but for convenience, a suggested programming flow is shown
in Figure 2.
Any step in this programming sequence may be skipped if the
default value is the desired value.
When programming an output frequency, the new frequency
will be valid on that output after all of the specified data values
have been written to all of the specified addresses. When
changing an output frequency, the output may transition
through one or more indeterminate frequencies between the
writing of the first byte and the last byte.
Note that some of the programming steps are not as
independent as they appear in the flow diagram. In particular,
addresses 48H, 53H, and 57H control both output frequencies
and drive strength. Because a byte is the smallest unit that
may be programmed through the serial interface, the user
must consider both the frequency setting and the output drive
strength when constructing the byte value to be written into
these particular address. It is not necessary to write more than
once to any given address, but that one write must have all of
the bits set correctly.
Example: configure CLKC for 33.8688 MHz and 2.5V output.
For address 48H, start with the value in Table 4: 89H (binary
10001001). Table 9 shows that bits 7 & 6 control the drive
st
r
engt
h,whi
chshoul
dbe‘
11’(
f
r
omTable 10). Therefore, the
final value is 11001001, which is C9H. This value is written
once.
Figure 2. Programming Flow
Default
Output Supply
Voltage settings if
2.5V (Table 3)
Drive Strength
settings for 2.5V
or EMI
(Tables 9, 4, 6, 8)
Reference CLK &
Crystal settings
(Table 2)
CLKC, D & E
Frequency settings
(Tables 4 - 6)
CLKF & G
Frequency settings
(Tables 7 - 8)
Table 2. Register Settings for VCXO and Reference
Reference Clock and VCXO
Crystal
Address
Manufacturer Part No.
Package
Specified CL
16H
17H
CLKIN (external reference), VCXO off
–
–
–
89
3A
Crystal, VCXO off
any
any
10.7 pF
88
4F
Crystal, VCXO off
any
any
12 pF
88
5F
Crystal, VCXO off (default)
any
any
12.6 pF
88
67
Crystal, VCXO off
any
any
14 pF
88
77
Crystal, VCXO on
KDS DSX530GA
5x3.2 mm
12.6 pF
88
3A
Crystal, VCXO on
KDS DSX530GA
5x3.2 mm
10.7 pF
88
2A
Crystal, VCXO on
RIVER FCX-03
5x3.2 mm
12 pF
88
41
Crystal, VCXO on
KDK
5x3.2 mm
12 pF
88
3A
Crystal, VCXO on
KDS
SMD-49
12 pF
88
39
Crystal, VCXO on
Ecliptek ECX-6277
SMD-49
12 pF
88
41
Table 3. Register Settings for Output Supply Voltages
Output
Output Supply Voltages
Address
41H
43H
CLKC
VDD1 = 3.3V
BF (default)
–
VDD1 = 2.5V
7F
–
CLKD, CLKE, CLKF, CLKG
VDD2 = 3.3V
–
A0 (default)
VDD2 = 2.5V
–
90
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