CC2550_06 Datasheet, PDF (28/55 Pages) Texas Instruments – Single Chip Low Cost Low Power RF Transmitter

CC2550
21 Output Power Programming
The RF output power level from the device has
two levels of programmability, as illustrated in
Figure 18. Firstly, the special PATABLE
register can hold up to eight user selected
output power settings. Secondly, the 3-bit
FREND0.PA_POWER value selects the
PATABLE entry to use. This two-level
functionality provides flexible PA power ramp
up and ramp down at the start and end of
transmission. All the PA power settings in the
PATABLE from index 0 up to the
FREND0.PA_POWER value are used.
The power ramping at the start and at the end
of a packet can be turned off by setting
FREND0.PA_POWER to 0 and then
programming the desired output power to
index 0 in the PATABLE.
Table 20 contains recommended PATABLE
settings for various output levels and
frequency bands. See Section 10.6 on page
16 for PATABLE programming details.
PATABLE must be programmed in burst mode
if you want to write to other entries than
PATABLE[0].
PATABLE(7)[7:0]
PATABLE(6)[7:0]
PATABLE(5)[7:0]
PATABLE(4)[7:0]
PATABLE(3)[7:0]
PATABLE(2)[7:0]
PATABLE(1)[7:0]
PATABLE(0)[7:0]
The PA uses this
setting.
Settings 0 to PA_POWER are
used during ramp-up at start of
transmission and ramp-down at
end of transmission, and for
OOK modulation.
Index into PATABLE(7:0)
e.g 6
PA_POWER[2:0]
in FREND0 register
The SmartRF® Studio software
should be used to obtain optimum
PATABLE settings for various
output powers.
Figure 18: PA_POWER and PATABLE
PRELIMINARY Data Sheet (Rev.1.2) SWRS039A
Page 28 of 54