Si5345-44-42-D-RM
Si5345
Rev. 1.0
113
Figure 55. Logic Diagram of the FINC/FDEC Masks
This is a 44-bit integer value which is directly added or subtracted from the N-divider when FINC or FDEC is set to
a 1. ClockBuilder Pro calculates the correct values for the N0 Frequency Step Word. Each N divider has the ability
to add or subtract up to a 44-bit value.
Nx_DELAY[15:0] is a 2s complement number that sets the output delay of MultiSynthx.
The delay in seconds is Nx_DELAY/(256 x Fvco) where Fvco is the VCO frequency in Hz. The maximum positive
and negative delay is ±(2
15
–1)/(256 x Fvco). ClockBuilder Pro calculates the correct value for this register.
Changing any of the Nx_DELAY values requires a SOFT_RST, a HARD_RST, or a power up sequence.
Register 0x033B-0x0340 N0 Frequency Step Word
Reg Address
Bit Field
Type
Name
Description
0x033B
7:0
R/W
N0_FSTEPW
44-bit Integer Number
0x033C
15:8
R/W
N0_FSTEPW
0x033D
23:16
R/W
N0_FSTEPW
0x033E
31:24
R/W
N0_ FSTEPW
0x033F
39:32
R/W
N0_ FSTEPW
0x0340
43:40
R/W
N0_ FSTEPW
Table 50. Registers that Follow the N0_FSTEPW Definitions
Register Address
Description
Size
Same as Address
0x0341-0x0346
N1 Frequency Step Word
44-bit Integer Number
0x033B-0x0340
0x0347-0x034C
N2 Frequency Step Word
44-bit Integer Number
0x033B-0x0340
0x034D-0x0352
N3 Frequency Step Word
44-bit Integer Number
0x033B-0x0340
0x0353-0x0358
N4 Frequency Step Word
44-bit Integer Number
0x033B-0x0340
Register 0x0359–0x35A N0 Delay Control
Reg Address
Bit Field
Type
Name
Description
0x0359
7:0
R/W
N0_DELAY[7:0]
Lower byte of N0_DELAY[15:0]
0x035A
15:8
R/W
N0_DELAY[15:8]
Upper byte of N0_DELAY[15:0]
FINC, 1Dh[0]
(self clear)
FDEC is the same as FINC
NxFINC
N_FSTEP_MSKx, 339h[4:0]
FINC pin,
pos edge trig