AD9520-5
Data Sheet
Rev. A | Page 60 of 76
Reg.
Addr.
(Hex)
Bits
Name
Description
[2:0] Prescaler P
Prescaler: DM = dual modulus and FD = fixed divide. The Prescaler P is part of the feedback divider.
Bit
2
Bit
1
Bit
0
Mode
Prescaler
0
FD
Divide-by-1.
0
1
FD
Divide-by-2.
0
1
0
DM
Divide-by-2 and divide-by-3 when A ≠ 0; divide-by-2 when A = 0.
0
1
DM
Divide-by-4 and divide-by-5 when A ≠ 0; divide-by-4 when A = 0.
1
0
DM
Divide-by-8 and divide-by-9 when A ≠ 0; divide-by-8 when A = 0.
1
0
1
DM
Divide-by-16 and divide-by-17 when A ≠ 0; divide-by-16 when A = 0.
1
0
DM
Divide-by-32 and divide-by-33 when A ≠ 0; divide-by-32 when A = 0 (default).
1
FD
Divide-by-3.
0x017
[7:2] STATUS
pin control
Selects the signal that appears at the STATUS pin. Register 0x01D[7] must be 0 to reprogram the STATUS pin.
Bit
7
Bit
6
Bit
5
Bit
4
Bit
3
Bit
2
Level or
Dynamic
Signal
Signal at STATUS Pin
0
LVL
Ground, dc (default).
0
1
DYN
N divider output (after the delay).
0
1
0
DYN
R divider output (after the delay).
0
1
DYN
A divider output.
0
1
0
DYN
Prescaler output.
0
1
0
1
DYN
PFD up pulse.
0
1
0
DYN
PFD down pulse.
0
X
LVL
Ground (dc). Used for all settings of these bits not otherwise specified in this table.
The selections that follow are also used for REFMON and LD pin control.
1
0
LVL
Ground (dc).
1
0
1
DYN
REF1 clock (differential reference when in differential mode).
1
0
1
0
DYN
REF2 clock (N/A in differential mode).
1
0
1
DYN
Selected reference to PLL (differential reference when in differential mode).
1
0
1
0
DYN
Unselected reference to PLL (not available in differential mode).
1
0
1
0
1
LVL
Status of selected reference (status of differential reference); active high.
1
0
1
0
LVL
Status of unselected reference (not available in differential mode); active high.
1
0
1
LVL
Status of REF1 frequency; active high.
1
0
1
0
LVL
Status of REF2 frequency; active high.
1
0
1
0
1
LVL
(Status of REF1 frequency) AND (status of REF2 frequency).
1
0
1
0
1
0
LVL
(DLD) AND (status of selected reference) AND (status of CLK).
1
0
1
0
1
LVL
Status of CLK frequency; active high.
1
0
1
0
LVL
Selected reference (low = REF1, high = REF2).
1
0
1
0
1
LVL
DLD; active high.
1
0
1
0
LVL
Holdover active; active high.
1
0
1
LVL
N/A. Do not use.
1
0
LVL
Vs (PLL power supply).
1
0
1
DYN
REF1 clock (differential reference when in differential mode).
1
0
1
0
DYN
REF2 clock (not available in differential mode).
1
0
1
DYN
Selected reference to PLL (differential reference when in differential mode).
1
0
1
0
DYN
Unselected reference to PLL (not available when in differential mode).
1
0
1
0
1
LVL
Status of selected reference (status of differential reference); active low.
1
0
1
0
LVL
Status of unselected reference (not available in differential mode); active low.
1
0
1
LVL
Status of REF1 frequency; active low.
1
0
LVL
Status of REF2 frequency; active low.
1
0
1
LVL
(Status of REF1 frequency) AND (status of REF2 frequency).
1
0
1
0
LVL
(DLD) AND (status of selected reference) AND (status of VCO).
1
0
1
LVL
Status of CLK frequency; active low.
1
0
LVL
Selected reference (low = REF2, high = REF1).
1
0
1
LVL
DLD; active low.
1
0
LVL
Holdover active; active low.
1
LVL
N/A. Do not use.