FS970X

Rev. 4.4

14/46

9.

Clock and Buzzer Generator

Clock Generator

4.0000 MHz

FS

F

TB

ENOSCO_

ENXTL_

FTB

TBDIV

FSDIV

Buzzer

VBAT

ENBP

CNTBP

FBP

CLK

DIVIDER

OSCO

2

XTALI

3

XTALO

4

BZR

58

OSCO

Graph 4 Clock Generator.

Clock generator is shown in Graph 4. It can be connected to a 4.000 MHz crystal oscillator to produce 4.000

MHz clock frequency. It can then be divided to FS, FTB, and FBP frequencies by a divider. Among these, FS is

used by ADC. (please refer to 8.4 for details.) FTB is used by digital circuits, such as the reference frequency of

frequency counter (please refer to section 9.1). FBP is used by buzzer to initiate buzzing.

FTB and FS are respectively controlled by ENXTAL_. TBDIV and FSDIV. The true value Chart is shown in

Chart 3:

ENXTAL_ TBDIV

FSDIV

L

L

1.0000 MHz

L

166.67 kHz

L

L

1.0000 MHz

H

83.33 kHz

L

H

125.0 kHz

L

166.67 kHz

L

H

125.0 kHz

H

83.33 kHz

H

X

0, (L)

X

0, (L)

Chart 3. FTB / FS generator true value Chart.