CYW20738
1.11 Clock Frequencies
The CYW20738 is set with crystal frequency of 24 MHz.
1.11.1 Crystal Oscillator
The crystal oscillator requires a crystal with an accuracy of ±20 ppm as defined by the Bluetooth specification. Two external load
capacitors in the range of 5 pF to 30 pF are required to work with the crystal oscillator. The selection of the load capacitors is crystal
dependent. Table 6 on page 13 shows the recommended crystal specification.
Figure 6. Recommended Oscillator Configuration—12 pF Load Crystal
22 pF
XIN
Crystal
XOUT
20 pF
Table 6. Reference Crystal Electrical Specifications
Parameter
Nominal frequency
Conditions
Minimum
Typical
Maximum
Unit
MHz
–
–
–
24.000
–
Oscillation mode
–
Fundamental
Frequency tolerance
Tolerance stability over temp
Equivalent series resistance
Load capacitance
@25°C
–
–
±10
±10
–
–
–
ppm
ppm
@0°C to +70°C
–
–
–
–
–
–
–
–
50
–
12
–
–
pF
Operating temperature range
Storage temperature range
Drive level
0
+70
+125
200
±10
2
°C
–40
–
–
°C
–
W
Aging
–
–
ppm/year
pF
Shunt capacitance
–
–
HID Peripheral Block
The peripheral blocks of the CYW20738 all run from a single 128 kHz low-power RC oscillator. The oscillator can be turned on at the
request of any of the peripherals. If the peripheral is not enabled, it shall not assert its clock request line.
The keyboard scanner is a special case in that it may drop its clock request line even when enabled and then reassert the clock
request line if a keypress is detected.
Document Number: 002-14891 Rev. *C
Page 13 of 42
CYPRESS [ CYPRESS ]
