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synthesis PLL is near the limit of generate
the frequency requested, and the PLL
should be recalibrated.
It
is
recommended
LOCK_CONTINOUS bit in the LOCK
15. Recommended RX settings for ISM frequencies
Shown in Table 9 are the recommended RX frequency synthesiser settings for a few
operating frequencies in the popular ISM bands. These settings ensure optimum
configuration of the synthesiser in receive mode for best sensitivity. For some settings of the
synthesiser (combinations of RF frequencies and reference frequency), the receiver
sensitivity is degraded. The FSK frequency separation is set to 64 kHz. The SmartRF®
Studio can be used to generate optimised configuration data as well. Also an application note
(AN011) and a spreadsheet are available from Chipcon generating configuration data for any
frequency giving optimum sensitivity.
ISM
Actual
Frequency
frequency
[MHz]
[MHz]
315
315.037200
433.3
433.302000
433.9
433.916400
434.5
434.530800
868.3
868.297200
868.95
868.918800
869.525
869.526000
869.85
869.840400
915
914.998800
*Note: When using high-side LO injection the data at DIO will be inverted.
Table 9. Recommended settings for ISM frequencies
that
the
Crystal
Low-side /
frequency
high- side
[MHz]
LO*
3.6864
High-side
7.3728
11.0592
14.7456
3.6864
Low-side
7.3728
11.0592
14.7456
3.6864
Low-side
7.3728
11.0592
14.7456
3.6864
Low-side
7.3728
11.0592
14.7456
3.6864
Low-side
7.3728
11.0592
14.7456
3.6864
High-side
7.3728
11.0592
14.7456
3.6864
Low-side
7.3728
11.0592
14.7456
3.6864
High-side
7.3728
11.0592
14.7456
3.6864
High-side
7.3728
11.0592
14.7456
SWRS048A
register
is
checked
frequencies and when changing between
RX and TX mode. If lock is not achieved, a
calibration should be performed.
Reference
Frequency word
divider
RX mode
REFDIV
FREQ
(decimal)
(decimal)
3
4194304
6
4194304
9
4194304
12
4194304
3
5775168
6
5775168
9
5775168
12
5775168
3
5775360
6
5775360
9
5775360
12
5775360
3
5783552
6
5783552
9
5783552
12
5783552
2
7708672
4
7708672
6
7708672
8
7708672
2
7716864
4
7716864
6
7716864
7716864
3
11583488
6
11583488
9
11583488
12
11583488
2
7725056
4
7725056
6
7725056
8
7725056
2
8126464
4
8126464
6
8126464
8
8126464
CC1000
when
changing
Frequency word
RX mode
FREQ
(hex)
400000
400000
400000
400000
580000
580000
580000
580000
582000
582000
582000
582000
584000
584000
584000
584000
75A000
75A000
75A000
75A000
75C000
75C000
75C000
75C000
B0C000
B0C000
B0C000
B0C000
75E000
75E000
75E000
75E000
7C0000
7C0000
7C0000
7C0000
Page 24 of 55
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