PCA5007 datasheet(33/112 Pages) PHILIPS

33 / 112 page

1998 Oct 07

Philips Semiconductors

Product speciﬁcation

Pager baseband controller

PCA5007

6.12.2

6 MHZ OSCILLATOR CONTROL REGISTER (OS6CON)

The OS6CON special function register is used to control the operation of the on-chip 6 MHz oscillator. The 6 MHz

oscillator can be controlled as follows:

• It can be enabled or disabled. Disabling this oscillator when the DC/DC converter is in standby mode and no port I/O

nor I2C-bus activity is required saves current.

• The frequency of the oscillator can be adjusted by setting the SFx bits accordingly

• The actual frequency of the oscillator can be measured by writing the MFR bit to logic 1.

Table 24 6 MHz Oscillator Control Register (OS6CON, SFR address D3H)

Table 25 Description of the OS6CON bits

6.12.3

6 MHZ OSCILLATOR MEASURED FREQUENCY REGISTER (OS6M0)

The actual frequency of the 6 MHz on-chip oscillator can be calculated from the value in the OS6M0 special function

Table 26 6 MHz Oscillator Measured Frequency Register (OS6M0, SFR address D4H)

The value stored in this SFR is the counted number of 6 MHz cycles during one 76.8 kHz period. The frequency of the

6 MHz oscillator is therefore f = MF

× 76800 Hz with a resolution of 76800 Hz.

76543210

ENB

−

SF4

SF3

SF2

SF1

SF0

MFR

BIT

SYMBOL

FUNCTION

OS6CON.7

ENB

Enable oscillator. If ENB = 1 then the function is enabled. The enable bit is only

cleared when the processor writes the bit to logic 0, or if the DC/DC converter is put into

‘OFF’ state and a reset is generated during the following power-up sequence.

OS6CON.6

−

unused

OS6CON.5

SF4

Set frequency. This 5-bit value adjusts the current of the ring oscillator and thus the

frequency. Writing a small value decreases the frequency. The nominal frequency of

6 MHz is assigned to code (SF4, SF3, SF2, SF1 SF0) = 00000. The resolution of the

frequency adjustment is 200 kHz per step, the range is approximately 3 to 9 MHz.

In order to start with the nominal frequency the MSB bit is inverted in this SFR.

OS6CON.4

SF3

OS6CON.3

SF2

OS6CON.2

SF1

OS6CON.1

SF0

OS6CON.0

MFR

Measure frequency. If a positive pulse is issued on this SFR-bit a frequency

measurement cycle is executed. The duration of this cycle is one period of 76.8 kHz.

The count of 6 MHz periods during the measurement cycle is reported back in OS6M0.

The bit must be reset by software.

76543210

MF7

MF6

MF5

MF4

MF3

MF2

MF1

MF0

PCA5007 датащи(PDF) 33 Page - NXP Semiconductors

PCA5007 датащи(HTML) 33 Page - NXP Semiconductors

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

датащи скачать

ссылки URL