PSKEY_ANA_FTRIM_OFFSET = (
f
actual
f
nominal
− 1) × 2
20
Equation 3.1: Crystal Calibration Using PSKEY_ANA_FTRIM_OFFSET
For a requested frequency of 2402MHz with an actual output of 2402.0168MHz the PSKEY_ANA_FTRIM_OFFSET
value is 7, see Equation 3.2.
PSKEY_ANA_FTRIM_OFFSET = ( 2402.0168
2402
− 1) × 2
20
≈ 7
Equation 3.2: Example of PSKEY_ANA_FTRIM_OFFSET Value for 2402.0168MHz
For a requested frequency of 2402MHz with an actual output of 2401.9832MHz the PSKEY_ANA_FTRIM_OFFSET
value is -7 (0xfff9), see Equation 3.3.
PSKEY_ANA_FTRIM_OFFSET = ( 2401.9832
2402
− 1) × 2
20
≈ −7
Equation 3.3: Example of PSKEY_ANA_FTRIM_OFFSET Value for 2401.9832MHz
3.3.2
Crystal Specification
Table 3.1 shows the specification for an external crystal.
Parameter
Min
Typ
Max
Unit
Frequency
16
26
32
MHz
Crystal load capacitance
-
9
-
pF
Frequency Stability
-
-
20
ppm
Frequency Tolerance
-
-
±20
ppm
Pullability
10
15
30
ppm/pF
Transconductance
2
-
-
mS
Table 3.1: Crystal Specification
Advance Information
This material is subject to CSR's non-disclosure agreement
© Cambridge Silicon Radio Limited 2011
Page 26 of 110
CS-209182-DSP1
CSR8640 BGA
Data Sheet