AK1590 Datasheet, PDF (17/36 Pages) Asahi Kasei Microsystems – 1GHz Delta-Sigma Fractional-N Frequency Synthesizer

[AK1590]
 Setup example
{DITH} = D[14] in <Address3> is set to “1” (DITH ON):
Digital Lock Detect Available
VCO frequency
180MHz
[REFIN] input
frequency
12.8MHz
{LDCKSEL[1:0]}
“00”
Calculation
180MHz > 12.8/(0+1) × 7 = 89.6MHz
{DITH} = D[14] in <Address3> is set to “0” (DITH OFF):
Digital Lock Detect Available
VCO frequency
180MHz
[REFIN] input
frequency
12.8MHz
{LDCKSEL[1:0]}
“00”
Calculation
180MHz > 12.8/(0+1) × 4 = 51.2MHz
Digital Lock Detect Unavailable
70MHz
32MHz
“10”
70MHz < 32/(2+1) × 7 = 74.67MHz
Digital Lock Detect Unavailable
60MHz
32MHz
“01”
60MHz < 32/(1+1) × 4 = 64MHz
Case: {LDCKSEL} = “00”
Reference clock
PFD clock
VCO divide clock
Phase detector output
Lock detect result
ï¼´
Invalid _Valid
Valid
Valid
Invalid
Invalid ^Valid
Fig. 8 Digital Lock Detect Operation
MS1478-E-01
17
2013/2