CC2500_06 Datasheet, PDF (11/84 Pages) Texas Instruments – Single Chip Low Cost Low Power RF Transceiver

CC2500
4.5 Low Power RC Oscillator
Tc = 25°C, VDD = 3.0 V if nothing else stated. All measurement results obtained using the CC2500EM reference design.
Parameter
Calibrated frequency
Frequency accuracy after
calibration
Temperature coefficient
Supply voltage coefficient
Initial calibration time
Min
Typ
Max Unit
Condition/Note
34.6 34.7
36
kHz Calibrated RC Oscillator frequency is XTAL
frequency divided by 750
+0.3
%
The RC oscillator contains an error in the
-10
calibration routine that statistically occurs in
17.3% of all calibrations performed. The given
maximum accuracy figures account for the
calibration error. Refer also to the CC2500
Errata Note.
+0.4
% / °C Frequency drift when temperature changes
after calibration
+3
% / V Frequency drift when supply voltage changes
after calibration
2
ms
When the RC Oscillator is enabled, calibration
is continuously done in the background as long
as the crystal oscillator is running.
Table 8: RC oscillator parameters
4.6 Frequency Synthesizer Characteristics
Tc = 25°C, VDD = 3.0 V if nothing else stated. All measurement results obtained using the CC2500EM reference design.
Parameter
Min Typ
Max Unit
Condition/Note
Programmed
frequency resolution
397 F_XOSC/
412
2¹⁶
Hz 26-27 MHz crystal.
Synthesizer frequency
±40
tolerance
ppm Given by crystal used. Required accuracy (including
temperature and aging) depends on frequency band and
channel bandwidth / spacing.
RF carrier phase noise
–78
dBc/Hz @ 50 kHz offset from carrier
–78
dBc/Hz @ 100 kHz offset from carrier
–81
dBc/Hz @ 200 kHz offset from carrier
–90
dBc/Hz @ 500 kHz offset from carrier
–100
dBc/Hz @ 1 MHz offset from carrier
–108
dBc/Hz @ 2 MHz offset from carrier
–116
dBc/Hz @ 5 MHz offset from carrier
–127
dBc/Hz @ 10 MHz offset from carrier
PLL turn-on / hop time
88.4
µs Time from leaving the IDLE state until arriving in the RX,
FSTXON or TX state, when not performing calibration.
Crystal oscillator running.
PLL RX/TX settling
9.6
µs Settling time for the 1·IF frequency step from RX to TX
time
PLL TX/RX settling
21.5
µs Settling time for the 1·IF frequency step from TX to RX
time
PLL calibration time
18739
XOSC Calibration can be initiated manually, or automatically
cycles before entering or after leaving RX/TX.
0.69 0.72 0.72
ms Min/typ/max time is for 27/26/26 MHz crystal frequency.
Table 9: Frequency synthesizer parameters
PRELIMINARY Data Sheet (Rev.1.2) SWRS040A
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