Datasheet

Data Sheet AD9520-0
Rev. A | Page 69 of 80
Reg.
Addr.
(Hex)
Bits Name Description
[4:0]
REFMON pin
control
Selects the signal that is connected to the REFMON pin.
Bit
4
Bit
3
Bit
2
Bit
1
Bit
0
Level or
Dynamic
Signal Signal at REFMON Pin
0 0 0 0 0 LVL Ground, dc (default).
0 0 0 0 1 DYN REF1 clock (differential reference when in differential mode).
0 0 0 1 0 DYN REF2 clock (N/A in differential mode).
0 0 0 1 1 DYN Selected reference to PLL (differential reference when in differential mode).
0 0 1 0 0 DYN Unselected reference to PLL (not available in differential mode).
0 0 1 0 1 LVL Status of selected reference (status of differential reference); active high.
0 0 1 1 0 LVL Status of unselected reference (not available in differential mode); active high.
0 0 1 1 1 LVL Status of REF1 frequency; active high.
0 1 0 0 0 LVL Status of REF2 frequency; active high.
0 1 0 0 1 LVL (Status of REF1 frequency) AND (status of REF2 frequency).
0 1 0 1 0 LVL (DLD) AND (status of selected reference) AND (status of VCO).
0 1 0 1 1 LVL Status of VCO frequency; active high.
0 1 1 0 0 LVL Selected reference (low = REF1, high = REF2).
0 1 1 0 1 LVL DLD; active high.
0 1 1 1 0 LVL Holdover active; active high.
0 1 1 1 1 LVL N/A. Do not use.
1 0 0 0 0 LVL V
S
(PLL power supply).
1 0 0 0 1 DYN
REF1 clock
(differential reference when in differential mode).
1 0 0 1 0 DYN
REF2 clock
(not available in differential mode).
1 0 0 1 1 DYN
Selected reference to PLL
(differential reference when in differential mode).
1
0
1
0
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 1 0 LVL Status of unselected reference (not available in differential mode); active low.
1 0 1 1 1 LVL Status of REF1 frequency; active low.
1 1 0 0 0 LVL Status of REF2 frequency; active low.
1 1 0 0 1 LVL
(Status of REF1 frequency) AND (status of REF2 frequency)
.
1 1 0 1 0 LVL
(DLD) AND (status of selected reference) AND (status of VCO)
.
1 1 0 1 1 LVL Status of VCO frequency; active low.
1 1 1 0 0 LVL Selected reference (low = REF2, high = REF1).
1 1 1 0 1 LVL DLD; active low.
1 1 1 1 0 LVL Holdover active; active low.
1 1 1 1 1 LVL N/A. Do not use.
0x01C 7
Disable
switchover
deglitch
Disables or enables the switchover deglitch circuit.
0: enables the switchover deglitch circuit (default).
1: disables the switchover deglitch circuit.
6 Select REF2
If Register 0x01C[5] = 0b, selects the reference for PLL when in manual; register selected reference control.
0: selects REF1 (default).
1: selects REF2.
5 Use REF_SEL pin
If Register 0x01C[4] = 0b (manual), sets the method of PLL reference selection.
0: uses Register 0x01C[6] (default).
1: uses REF_SEL pin.
4
Enable automatic
reference
switchover
Automatic or manual reference switchover. Single-ended reference mode must be selected by Register 0x01C[0] = 0b.
0: manual reference switchover (default).
1: automatic reference switchover. Setting this bit also powers on REF1 and REF2 and overrides the settings in Register 0x01C[2:1].
3 Stay on REF2
Stays on REF2 after switchover.
0: returns to REF1 automatically when REF1 status is good again (default).
1: stays on REF2 after switchover. Does not automatically return to REF1.
2 Enable REF2
This bit turns the REF2 power on. This bit is overridden when automatic reference switchover is enabled.
0: REF2 power off (default).
1: REF2 power on.
1 Enable REF1
This bit turns the REF1 power on. This bit is overridden when automatic reference switchover is enabled.
0: REF1 power off (default).
1: REF1 power on.
0
Enable
differential ref
Selects the PLL reference mode, differential or single-ended. Register 0x01C[2:1] should be cleared when this bit is set.
0: single-ended reference mode (default); 1: differential reference mode.