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synthesis PLL is near the limit of generate
the frequency requested, and the PLL
should be recalibrated.
It is recommended that the
LOCK_CONTINOUS
bit in the LOCK
register is checked when changing
frequencies and when changing between
RX and TX mode. If lock is not achieved, a
calibration should be performed.
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
Frequency
[MHz]
Actual
frequency
[MHz]
Crystal
frequency
[MHz]
Low-side /
high- side
LO*
Reference
divider
REFDIV
(decimal)
Frequency word
RX mode
FREQ
(decimal)
Frequency word
RX mode
FREQ
(hex)
315 315.037200
3.6864
High-side
3 4194304 400000
7.3728
6
4194304
400000
11.0592
9
4194304
400000
14.7456
12
4194304
400000
433.3 433.302000
3.6864
Low-side 3
5775168
580000
7.3728
6
5775168
580000
11.0592
9
5775168
580000
14.7456
12
5775168
580000
433.9 433.916400
3.6864
Low-side 3
5775360
582000
7.3728
6
5775360
582000
11.0592
9
5775360
582000
14.7456
12
5775360
582000
434.5 434.530800
3.6864
Low-side 3
5783552
584000
7.3728
6
5783552
584000
11.0592
9
5783552
584000
14.7456
12
5783552
584000
868.3 868.297200
3.6864
Low-side 2
7708672
75A000
7.3728
4
7708672
75A000
11.0592
6
7708672
75A000
14.7456
8
7708672
75A000
868.95 868.918800
3.6864 High-side 2
7716864
75C000
7.3728
4
7716864
75C000
11.0592
6
7716864
75C000
14.7456
7716864
75C000
869.525 869.526000
3.6864 Low-side
3
11583488
B0C000
7.3728
6
11583488
B0C000
11.0592
9
11583488
B0C000
14.7456
12
11583488
B0C000
869.85 869.840400
3.6864 High-side 2
7725056
75E000
7.3728
4
7725056
75E000
11.0592
6
7725056
75E000
14.7456
8
7725056
75E000
915 914.998800
3.6864
High-side
2 8126464 7C0000
7.3728
4
8126464
7C0000
11.0592
6
8126464
7C0000
14.7456
8
8126464
7C0000
*Note: When using high-side LO injection the data at DIO will be inverted.
Table 9. Recommended settings for ISM frequencies