King Billion Electronics Co., Ltd

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HE847701

HE80000 SERIES

March 26, 2004

Page 15 of 29

V1.03

This specification is subject to change without notice. Please contact sales person for the latest version before use.

The RC oscillator has a built-in capacitor. An external resistor is needed to connect from FXI to GND to

determine the oscillation frequency. The capacitance of internal RC oscillator is selected by mask option

MO_RCAP[2..0].

MO_RCAP[2..0] Internal RC Cap. OSC. (pF)

000

2

001

4

010

7

011

14

100

20

101

40

110

50

111

60

The following table shows the combinations of R and C, and the resulting frequency. Please note that

oscillation frequency in the table only represents oscillation frequencies of certain samples. The actual

oscillation frequency may vary up to ±15% from lot to lot due to process parameter variations. User must

take this into consideration when using this chip in applications.

Ring Oscillator Frequency Table

40

20

14

7

4

2

30.20

0.8

1.5

2.0

3.0

4.0

5.0 MHz

19.92

1.2

2.2

2.8

4.4

5.6

7.0 MHz

9.98

2.3

4.0

5.1

7.5

9.4 11.4 MHz

Two types of oscillator, crystal and RC, can be used as slow clock by mask option MO_SXTAL. If used

for time keeping function or other applications that required the accurate timing, crystal oscillator is

recommended. If the timing accuracy is not important, then RC type oscillator can be used to reduce cost.

MO_SXTAL

Slow clock type

0

R/C oscillator

1

Crystal oscillator

SXI

SXI

SXO

SXO

Crystal Osc.

RC Osc.

With two clock sources available, the system can switch among operation modes of Fast, Slow, Idle, and

Sleep modes by the setting of OP1 and OP2 registers as shown in tables below to suit the needs of

application such as power saving, etc.