CYWUSB6953_10 datasheet(24/68 Pages) CYPRESS

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CYRF69103

Document #: 001-07611 Rev *F

Page 24 of 68

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

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.

F8h

F9h

FAh

FBh

FCh

FDh

FEh

FFh

Table 0

Table 1

Table 2

Table 3

Table 4

Table 5

Table 6

Table 7

Silicon ID

[15-8]

Silicon ID

[7-0]

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

LPOSCTR

at 3.30V

32 kHz

LPOSCTR

at 3.00V

32 kHz

LPOSCTR

at 2.85V

32 kHz

LPOSCTR

at 2.70V

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