
ADF4193
MUX REGISTER (R6)
Rev. B | Page 21 of 28
0
DB15
M13
DB14
M12
DB13
M11
DB12
M10
DB11
0
DB10
0
DB9
0
DB8
0
DB7
0
DB6
M4
DB5
M3
DB4
M2
DB3
M1
DB2
C3 (1)
DB1
C2 (1)
DB0
C1 (0)
RESERVED
MUX
OUT
CONTROL
BITS
SIGMA-DELTA
AND
LOCK DETECT MODES
0
1
1
M10
0
1
0
M11
0
0
0
ALL OTHER STATES
M12
0
0
1
M13
INIT STATE, DITHER OFF,
3ns LOCK DETECT THRESHOLD
DITHER ON
10ns LOCK DETECT THRESHOLD
RESERVED
SIGMA-DELTA MODES
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
M4
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
M3
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
M2
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
M1
3-STATE
DIGITAL LOCK DETECT
N DIVIDER OUTPUT
LOGIC HIGH
R COUNTER
RESERVED
SERIAL DATA OUT
LOGIC LOW
R DIVIDER/2 OUTPUT
N DIVIDER/2 OUTPUT
RESERVED
RESERVED
ICP TIMEOUT SIGNAL
SW1/2 TIMEOUT SIGNAL
SW3 TIMEOUT SIGNAL
RESERVED
MUX
OUT
Figure 35. MUX Register (R6)
With C3, C2, and C1 set to 1, 1, 0, respectively, the MUX
register is programmed.
Σ-Δ and Lock Detect Modes
Bit DB15 to Bit DB12 are used to reconfigure certain PLL
operating modes. In the initialization sequence after power is
applied to the chip, the four bits must first be programmed to
all zeros. This initializes the PLL to a known state with dither
off in the Σ-Δ modulator and a 3 ns PFD error threshold in the
lock detect circuit.
To turn on dither in the Σ-Δ modulator, an additional write
should be made to Register R6 to program bits [DB15:DB12] =
[0011]. However, for lowest noise operation, it is best to leave
dither off.
To change the lock detect threshold from 3 ns to 10 ns, a
separate write to R6 should be performed to program bits
[DB15:DB12] = [1001]. This should be done for reliable lock
detect operation when the RF frequency is <2 GHz.
A write to R6 that programs bits [DB15:DB12] = [0000] returns
operation to the default state with both dither off and a 3 ns
lock detect threshold.
Reserved Bits
The reserved bits must all be set to 0 for normal operation.
MUX
OUT
Modes
These bits control the on-chip multiplexer. See Figure 35 for the
truth table. This pin is useful for diagnosis because it allows the
user to look at various internal points of the chip, such as the
R divider and INT divider outputs.
In addition, it is possible to monitor the programmed timeout
counter intervals on MUX
OUT
. For example, if the ICP timeout
counter was programmed to 65 (with a 26 MHz PFD), then
following the next write to R0, a pulse width of 10 μs would be
observed on the MUX
OUT
pin.
Digital lock detect is available via the MUX
OUT
pin.