CY28301
Document #: 38-07011 Rev. *C
Page 5 of 15
CY28301 Serial Configuration Map
1. The serial bits will be read by the clock driver in the following
order:
Byte 0 – Bits 7, 6, 5, 4, 3, 2, 1, 0
Byte 1 – Bits 7, 6, 5, 4, 3, 2, 1, 0
Byte N – Bits 7, 6, 5, 4, 3, 2, 1, 0
2. All unused register bits (reserved and N/A) should be
written to a “0” level.
3. All register bits labeled “Initialize to 0" must be written to “0”
during initialization.
Byte 0: Control Register 0
Bit
Pin#
Name
Default
Description
Bit 7
–
SEL1
0
See 5
Bit 6
–
SEL0
0
See 5
Bit 5
–
Reserved
0
Reserved
Bit 4
–
Reserved
0
Reserved
Bit 3
–
FS_Override
0
0 = Select operating frequency by FS[1:0] input pins
1 = Select operating frequency by SEL[1:0] settings
Bit 2
–
Spread Select2
0
‘000’ = Normal (spread off)
‘001’ = Test mode
‘010’ = Reserved
‘011’ = Three-stated
‘100’ = –0.5%
‘101’ = –0.75%
‘110’ = –1.0%
‘111’ = –0.3%
Bit 1
–
Spread Select1
0
Bit 0
–
Spread Select0
0
Byte 1: Control Register 1
Bit
Pin#
Name
Default
Description
Bit 7
56
Latched FS1 input
X
Latched FS[1:0] inputs. These bits are Read-only.
Bit 6
34
Latched FS0 input
X
Bit 5
–
Reserved
0
Reserved
Bit 4
–
Reserved
0
Reserved
Bit 3
–
Reserved
0
Reserved
Bit 2
–
Reserved
0
Reserved
Bit 1
56
REF
1
(Active/Inactive)
Bit 0
56
REF_DRV
0
REF Clock output drive strength
0 = Normal
1= High drive
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