Skyworks Si5341 - Dividers

2.1 Dividers
There are five divider classes within the Si5341/40. See Figure 2.2 Si5340 Detailed Block Diagram on page 11 for a block diagram
that shows all of these dividers.
• 1. Wide range input dividers Pfb, P2, P1, P0
• Only integer divider values
• Range is from 1 to 2
16
– 1
• Since the input to the phase detector needs to be
> 10 MHz, the practical range is limited to ~75 on the high side.
• Each divider has an update bit that must be written to cause a newly written divider value to take effect.
2. Narrow range input divider Pxaxb
• Only divides by 1, 2, 4, 8
3. Feedback M divider
• Ultra low jitter in fractional and integer modes
• MultiSynth divider
• Integer or fractional divide values
• 44 bit numerator, 32 bit denominator
• Practical range limited by phase detector range of 10–120 MHz and VCO range of 13500–14256 MHz
• This divider has an update bit that must be written to cause a newly written divider value to take effect.
4. Output N dividers
• Ultra low jitter in fractional and integer modes
• MultiSynth divider
• Integer or fractional divide values
• 44 bit numerator, 32 bit denominator
• Min value is 10
• Maximum value is 2
12
– 1
• Each N divider has an update bit that must be written to cause a newly written divider value to take effect. In addition there is
a global update bit that when written updates all N dividers.
5. Output R divider
• Only even integer divide values
• Min value is 2
• Maximum value is 2
25
– 2
Additionally, FSTEPW can be used to adjust the nominal output frequency in DCO mode. See Section 6. Digitally Controlled
Oscillator (DCO) Modes for more information and block diagrams on DCO mode.
Si5341, Si5340 Rev D Family Reference Manual • Functional Description
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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