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REGISTER 10—AFC REGISTER
MAX_AFC_RANGE
...
MA3
MA2
MA8
0
...
0
0
0
...
0
1
0
...
0
1
0
...
1
0
.
...
.
.
.
...
.
.
.
...
.
.
1
...
1
0
1
...
1
1
1
...
1
1
•
The AFC_SCALING_FACTOR can be expressed as
AFC
_
SCALING
_
FACTOR
•
The settings for KI and KP affect the AFC settling time and
AFC accuracy. The allowable range for each parameter is
KI > 6 and KP < 7.
•
The recommended settings for optimal AFC performance
are KI = 11 and KP = 4. To trade off between AFC settling
time and AFC accuracy, the KI and KP parameters can be
adjusted from the recommended settings (staying within
the allowable range) such that
AFC Correction Range = MAX_AFC_RANGE × 500 Hz
KP
KI
KP3
KP2
KP1
KP
KI4
KI3
0
0
0
2^0
0
0
0
0
0
0
1
2^1
.
.
.
.
.
...
1
1
1
1
2^7
1
MAX_AFC_RANGE
MA1
1
1
0
2
1
3
0
4
.
.
.
.
.
.
1
253
0
254
1
255
Figure 72. Register 10—AFC Register Map
⎛
×
⎞
24
2
500
⎜ ⎜
⎟ ⎟
=
Round
⎝
⎠
XTAL
AFC_SCALING_FACTOR
KI2
KI1
KI
0
0
2^0
0
1
2^1
.
.
...
1
1
2^15
...
M3
M12
0
...
0
0
...
0
0
...
0
0
...
1
.
...
.
.
...
.
.
...
.
1
...
1
1
...
1
1
...
1
•
When RF_DIVIDE_BY_2 (Register 1, Bit DB18) is enabled,
the programmed AFC correction range is halved. The user
must account for this halving by doubling the programmed
MAX_AFC_RANGE value.
•
Signals that are within the AFC pull-in range but outside
the IF filter bandwidth are attenuated by the IF filter. As a
result, the signal can be below the sensitivity point of the
receiver and, therefore, not detectable by the AFC.
Rev. 0 | Page 55 of 60
ADDRESS
AE1
AFC_EN
0
AFC OFF
1
AFC ON
AFC_SCALING_
M2
M1
FACTOR
0
1
1
1
0
2
1
1
3
0
0
4
.
.
.
.
.
.
.
.
.
0
1
4093
1
0
4094
1
1
4095
ADF7021-V
BITS
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