Datasheet

AD9520-0 Data Sheet
Rev. A | Page 68 of 80
Reg.
Addr.
(Hex)
Bits Name Description
[5:0] LD pin control Selects the signal that is connected to the LD pin.
Bit
5
Bit
4
Bit
3
Bit
2
Bit
1
Bit
0
Level or
Dynamic
Signal Signal at LD Pin
0 0 0 0 0 0 LVL Digital lock detect (high = lock; low = unlock, default).
0 0 0 0 0 1 DYN P-channel, open-drain lock detect (analog lock detect).
0 0 0 0 1 0 DYN N-channel, open-drain lock detect (analog lock detect).
0 0 0 0 1 1 HIZ Tristate (high-Z) LD pin.
0 0 0 1 0 0 CUR Current source lock detect (110 µA when DLD is true).
0 X X X X X LVL Ground (dc). Used for all settings of these bits that are not otherwise specified in this table.
The selections that follow are also used for REFMON and STATUS pin control.
1 0 0 0 0 0 LVL Ground (dc).
1
0
0
0
0
1
DYN
REF1 clock (differential reference when in differential mode).
1
0
0
0
1
0
DYN
REF2 clock (N/A in differential mode).
1 0 0 0 1 1 DYN Selected reference to PLL (differential reference when in differential mode).
1 0 0 1 0 0 DYN Unselected reference to PLL (not available in differential mode).
1 0 0 1 0 1 LVL Status of selected reference (status of differential reference); active high.
1 0 0 1 1 0 LVL Status of unselected reference (not available in differential mode); active high.
1 0 0 1 1 1 LVL Status of REF1 frequency; active high.
1 0 1 0 0 0 LVL Status of REF2 frequency; active high.
1 0 1 0 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 VCO).
1 0 1 0 1 1 LVL Status of VCO frequency; active high.
1 0 1 1 0 0 LVL Selected reference (low = REF1, high = REF2).
1 0 1 1 0 1 LVL DLD; active high.
1 0 1 1 1 0 LVL Holdover active; active high.
1 0 1 1 1 1 LVL N/A. Do not use.
1 1 0 0 0 0 LVL V
S
(PLL power supply).
1 1 0 0 0 1 DYN
REF1 clock
(differential reference when in differential mode).
1 1 0 0 1 0 DYN
REF2 clock
(not available in differential mode).
1 1 0 0 1 1 DYN
Selected reference to PLL
(differential reference when in differential mode).
1 1 0 1 0 0 DYN
Unselected reference to PLL
(not available when in differential mode).
1
1
0
1
0
1
LVL
Status of selected reference (status of differential reference); active low.
1
1
0
1
1
0
LVL
Status of unselected reference (not available in differential mode); active low.
1 1 0 1 1 1 LVL Status of REF1 frequency; active low.
1 1 1 0 0 0 LVL Status of REF2 frequency; active low.
1 1 1 0 0 1 LVL
(Status of REF1 frequency) AND (status of REF2 frequency)
.
1 1 1 0 1 0 LVL
(DLD) AND (status of selected reference) AND (status of VCO)
.
1 1 1 0 1 1 LVL Status of VCO frequency; active low.
1 1 1 1 0 0 LVL Selected reference (low = REF2, high = REF1).
1 1 1 1 0 1 LVL DLD; active low.
1 1 1 1 1 0 LVL Holdover active; active low.
1 1 1 1 1 1 LVL N/A. Do not use.
0x01B 7
Enable VCO
frequency
monitor
Enables or disables the VCO frequency monitor.
0: disables the VCO frequency monitor (default).
1: enables the VCO frequency monitor.
6
Enable REF2
(
REFIN
) frequency
monitor
Enables or disables the REF2 frequency monitor.
0: disables the REF2 frequency monitor (default).
1: enables the REF2 frequency monitor.
5
Enable REF1
(REFIN)
frequency
monitor
REF1 (REFIN) frequency monitor enabled; this is for both REF1 (single-ended) and REFIN (differential) inputs (as selected by
differential reference mode).
0: disables the REF1 (REFIN) frequency monitor (default).
1: enables the REF1 (REFIN) frequency monitor.