CYWUSB6953_10 Datasheet, PDF (24/68 Pages) Cypress Semiconductor – Programmable Radio on Chip Low Power

CYRF69103
15. Clocking
The CYRF69103 internal oscillator outputs two frequencies,
the Internal 24 MHz Oscillator and the 32 kHz Low power
Oscillator.
The Internal 24 MHz Oscillator is designed such that it may be
trimmed to an output frequency of 24 MHz over temperature
and voltage variation. The Internal 24 MHz Oscillator accuracy
is 24 MHz –22% to +10% (between 0°–70°C). No external
components are required to achieve this level of accuracy.
Firmware is responsible for selecting the correct trim values
from the User row to match the power supply voltage in the
end application and writing the values to the trim registers
IOSCTR and LPOSCTR.
The internal low speed oscillator of nominally 32 kHz provides
a slow clock source for the CYRF69103 in suspend mode.
This is used to generate a periodic wakeup interrupt and
provide a clock to sequential logic during power up and power
down events when the main clock is stopped. In addition, this
oscillator can also be used as a clocking source for the Interval
Timer clock (ITMRCLK) and Capture Timer clock (TCAPCLK).
The 32 kHz Low power Oscillator can operate in low power
mode or can provide a more accurate clock in normal mode.
The Internal 32 kHz Low power Oscillator accuracy ranges
from –53.12% to +56.25%. The 32 kHz low power oscillator
can be calibrated against the internal 24 MHz oscillator or
another timing source if desired.
CYRF69103 provides the ability to load new trim values for the
24 MHz oscillator based on voltage. This allows Vdd to be
monitored and have firmware trim the oscillator based on
voltage present. The IOSCTR register is used to set trim
values for the 24 MHz oscillator. CYRF69103 is initialized with
3.30V trim values at power on, then firmware is responsible for
transferring the correct set of trim values to the trim registers
to match the application’s actual Vdd. The 32 kHz oscillator
generally does not require trim adjustments versus voltage but
trim values for the 32 kHz are also stored in Supervisory ROM.
Figure 15-1. SROM Table
F8h
F9h
FAh
FBh
FCh
FDh
FEh
FFh
Table 0
Silicon ID
[15-8]
Silicon ID
[7-0]
Table 1
Table 2
ROegpieornaVtainligd
24 MHz
IOSCTR
at 3.30V
24 MHz
IOSCTR
at 3.00V
24 MHz
IOSCTR
at 2.85V
24 MHz
IOSCTR
at 2.70V
32 kHz 32 kHz 32 kHz 32 kHz
Table 3 LPOSCTR LPOSCTR LPOSCTR LPOSCTR
at 3.30V at 3.00V at 2.85V at 2.70V
Table 4
Table 5
Table 6
Table 7
To improve the accuracy of the IMO, new trim values are loaded based on supply voltage to the part. For this, firmware needs to
make modifications to two registers:
1. The internal oscillator trim register at location 0x34.
2. The gain register at location 0x38.
Document #: 001-07611 Rev *F
Page 24 of 68
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