CY24239 Cypress Semiconductor, CY24239 Datasheet - Page 6

• Manufacturer Part Number: CY24239
• Description: Spread Spectrum Frequency Timing Generator
• Manufacturer: Cypress Semiconductor

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Writing Data Bytes
Each bit in Data Bytes 0–7 controls a particular device function
except for the “reserved” bits which must be written as a logic
0. Bits are written MSB (most significant bit) first, which is bit 7.
Table 5 gives the bit formats for registers located in Data Bytes
0–7.
Table 5. Data Bytes 0–7 Serial Configuration Map
Document #: 38-07038 Rev. **
Data Byte 0
Data Byte 1
Data Byte 2
Data Byte 3
Bit(s)
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
7
6
5
4
3
Pin No.
33, 32,
25, 24
46
49
51
52
16
14
13
12
29
30
11
--
--
--
--
--
--
--
--
--
--
--
--
--
--
--
8
9
Affected Pin
SDRAM12:15
SDRAM16
Pin Name
Test Mode
CPU_F
48MHz
24MHz
PCI_F
CPU2
CPU1
PCI5
PCI4
PCI3
PCI2
PCI1
PCI0
--
--
--
--
--
--
--
--
--
--
--
--
--
--
(Reserved)
SEL2
SEL1
SEL0
Frequency Table Selection
SEL3
(Reserved)
--
--
--
--
--
Clock Output Disable
Clock Output Disable
Clock Output Disable
Clock Output Disable
(Reserved)
Clock Output Disable
Clock Output Disable
Clock Output Disable
Clock Output Disable
Clock Output Disable
Clock Output Disable
Clock Output Disable
(Reserved)
(Reserved)
Clock Output Disable
Clock Output Disable
Clock Output Disable
Control Function
Table 6 details additional frequency selections that are avail-
able through the serial data interface.
Table 7 details the select functions for Byte 0, bits 1 and 0.
Frequency Con-
trolled by FS(3:0) Ta-
ble 2
Normal
LOW
LOW
LOW
LOW
LOW
LOW
LOW
LOW
LOW
LOW
LOW
LOW
LOW
LOW
--
--
--
--
--
--
--
--
--
0
Refer to Table 6
Refer to Table 6
Refer to Table 6
Refer to Table 6
Bit Control
Frequency Con-
trolled by SEL(3:0)
Table 6
Three-stated
Active
Active
Active
Active
Active
Active
Active
Active
Active
Active
Active
Active
Active
Active
1
--
--
--
--
--
--
--
--
--
CY24239
Page 6 of 15
Default
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
0
1
1
1
1
1
1
1
0
0
1
1
1