BCM89071A1CUBXGT Datasheet, PDF (35/69 Pages) Cypress Semiconductor – Single-Chip Automotive Grade Bluetooth Transceiver and Baseband Processor

BCM89071 Data Sheet
Frequency References
Section 6: Frequency References
The BCM89071 uses two different frequency references for normal and low-power operational modes. An
external crystal or frequency reference driven by a Temperature Compensated Crystal Oscillator (TCXO) signal
is used to generate the radio frequencies and normal operation clocking. Either an external 32.768 kHz or fully
integrated internal Low-Power Oscillator (LPO) is used for low-power mode timing.
Crystal Interface and Clock Generation
The BCM89071 uses a fractional-N synthesizer to generate the radio frequencies, clocks, and data/packet
timing, enabling it to operate from any of a multitude of frequency sources. The source can be external, such as
a TCXO, or a crystal interfaced directly to the device. The default frequency reference setting is for a 20 MHz
crystal or TCXO. The signal characteristics for the crystal interface are listed in Table 3.
Table 3: Crystal Interface Signal Characteristics
Parameter
Crystal
External Frequency Reference
Units
Acceptable frequencies
12–52 MHz in 2 ppm^a steps 12–52 MHz in 2 ppm^a steps
–
Crystal load capacitance 12 (typical)
N/A
pF
ESR
60 (max)
–

Power dissipation
200 (max)
–
W
Input signal amplitude
N/A
400 to 2000
mVp-p
2000 to 3300 (requires a 10 pF DC
blocking capacitor to attenuate the signal)
Signal type
N/A
Square-wave or sine-wave
–
Input impedance
N/A
1
M
2
pF
Phase noise
N/A
–
–
@ 1 kHz
N/A
@ 10 kHz
N/A
@ 100 kHz
N/A
@ 1 MHz
N/A
< –120^b
< –131^b
< –136^b
< –136^b
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
Auto-detection frequencies
when using external LPO^c
12, 13, 14.4, 15.36, 16.2, 12, 13, 14.4, 15.36, 16.2, 16.8, 18, 19.2, MHz
16.8, 18, 19.2, 19.44, 19.68, 19.44, 19.68, 19.8, 20, 24, 26, 33.6, 37.4,
19.8, 20, 24, 26, 33.6, 37.4, and 38.4
and 38.4
Tolerance without frequency ±20
±20
ppm
trimming^d
Initial frequency tolerance ±50
±50
ppm
trimming range
a. The frequency step size is approximately 80 Hz resolution.
b. With a 26 MHz reference clock. For a 13 MHz clock, subtract 6 dB. For a 52 MHz clock, add 6 dB.
Broadcom^®
April 16, 2015 • 89071-DS106-R
Baseband Transceiver and Baseband Processor
Page 34