RFM22 Datasheet, PDF (149/150 Pages) –

RFM22
13. Description: Phase Noise at 100 kHz and 1 MHz offsets can occasionally jump to be out of spec by 5 dB.
Impacts: The 5 dB shift may impact adjacent channel selectivity and TX spectral mask.
Workaround: The issue has a bi-modal nature and can toggle between two states of phase noise.
Resolution: Will be fixed in the next revision.
14. Description: Some non-standard frequencies are not supported.
Impacts: Operation in frequencies between 240–280 MHz and 480–560 MHz should be avoided.
Workaround: These are non-standard bands and should result in no customer impact; no workaround at this
time.
Resolution: Will be fixed in the next revision.
15. Description: RSSI is not correct using default settings.
Impacts: No impact.
Workaround: Set the following registers: Reg 6Ah lnacomp[3:0] = 0010 and pgathres[1:0] = 11.
Resolution: Will be fixed in the next revision.
16. Description: The reference design listed in the data sheet does not meet the specified harmonic suppression as
listed in the data sheet.
Impacts: May not meet harmonic specification with listed reference design.
olution: Change Low Pass Filter Reference Design.
17. Description: LBD voltage read-back can occasionally be incorrect. If the LBD battery voltage register is read
during the same cycle that the register is being updated, it will read the previously read value and not the updated
value. The LBD measurement cycle is 250  s and the update period is 30  s.
Impacts: May need to use majority polling or use the LBD interrupt instead.
Workaround: Read the register two or three consecutive times to ensure it is correct or use the LBD interrupt.
Resolution: Will be fixed in the future revision.
18. Description: For TX data rates higher than 100 kbps a register change is required. The cpcurr[1:0] bits in Reg
58h should be changed to 11 (default = 01).
Impacts: May slightly degrade phase noise in the 100 to 300 kHz region.
Workaround: Change Reg 58h to 11.
Resolution: None planned.
Workaround: If random selection of the TX antenna is not desired, then a single antenna may be manually
selected by using the antdiv register in 08h.
Resolution: Will be fixed in the next revision.
19. Description: Use the PA Reference Design in data sheet revision 0.4
Impacts: Not using the reference design on data sheet 0.4 may create a maximum voltage swing higher than
expected on the PA output.
Workaround: See data sheet.
Resolution: Informational only.
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