Crystal Oscillator; Low Power Rc Oscillator - Texas Instruments CC2500 TK Manual

4.4

Crystal Oscillator

Tc = 25C, VDD = 3.0 V if nothing else stated.
Parameter Min
Crystal frequency 26
Tolerance
ESR
Start-up time
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
([4]).
Parameter
Calibrated frequency
Frequency accuracy after
calibration
Temperature coefficient
Supply voltage coefficient
Initial calibration time
Typ Max Unit Condition/Note
26 27 MHz
±40 ppm This is the total tolerance including a) initial tolerance, b) crystal
loading, c) aging, and d) temperature dependence.
The acceptable crystal tolerance depends on RF frequency and
channel spacing / bandwidth.

100
150 µs Measured on CC2500EM reference design ([4]) using crystal
AT-41CD2 from NDK.
This parameter is to a large degree crystal dependent.
Table 7: Crystal Oscillator Parameters
Min Typ Max
34.7 34.7 36
-1 /
+10
+0.4
+3
2
Table 8: RC Oscillator Parameters
SWRS040C
Unit Condition/Note
kHz Calibrated RC oscillator frequency is XTAL
frequency divided by 750
% The RC oscillator contains an error in the
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 Notes.
% / C
Frequency drift when temperature changes
after calibration
% / V Frequency drift when supply voltage changes
after calibration
ms When the RC oscillator is enabled, calibration
is continuously done in the background as long
as the crystal oscillator is running.
CC2500
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