HT66F016 datasheet(30/116 Pages) HOLTEK

30 / 116 page

HT66F016/HT66F017/HT68F016/HT68F017

Rev. 1.00

May 14, 2012

Oscillator

Various oscillator options offer the user a wide range of

functions according to their various application require-

ments. The flexible features of the oscillator functions

ensure that the best optimisation can be achieved in

terms of speed and power saving. Oscillator selections

and operation are selected through a combination of

configuration options and registers.

Oscillator Overview

In addition to being the source of the main system clock

the oscillators also provide clock sources for the Watch-

dog Timer and Time Base Interrupts. External oscilla-

tors requiring some external components as well as fully

integrated internal oscillators, requiring no external

components, are provided to form a wide range of both

fast and slow system oscillators. All oscillator options

are selected through the configuration options. The

higher frequency oscillators provide higher performance

but carry with it the disadvantage of higher power re-

quirements, while the opposite is of course true for the

lower frequency oscillators. With the capability of dy-

namically switching between fast and slow system

clock, the device has the flexibility to optimize the perfor-

mance/power ratio, a feature especially important in

power sensitive portable applications.

Type

Name

Freq.

Pins

External Crystal

HXT

400kHz~

20MHz

OSC1/

OSC2

Internal High

Speed RC

HIRC

8MHz

Internal Low

Speed RC

LIRC

32kHz

Oscillator Types

System Clock Configurations

There are methods of generating the system clock, two

high speed oscillators and one low speed oscillators.

The high speed oscillators are the external crystal/ce-

ramic oscillator - HXT and the internal 8MHz RC oscilla-

tor - HIRC. The low speed oscillator is the internal

32kHz oscillator - LIRC. Selecting whether the low or

high speed oscillator is used as the system oscillator is

implemented using the HLCLK bit and CKS2~CKS0 bits

in the SMOD register and as the system clock can be

dynamically selected.

L I R C

H i g h S p e e d

O s c i l l a t i o n

L o w S p e e d

O s c i l l a t i o n

f H

f H / 6 4

f H / 3 2

f H / 1 6

f H / 8

f H / 4

f H / 2

6 - s t a g e P r e s c a l e r

f S U B

H i g h S p e e d O s c i l l a t i o n

C o n f i g u r a t i o n O p t i o n

f S Y S

H L C L K ,

C K S 2 ~ C K S 0 b i t s

H X T

H I R C

F a s t W a k e - u p f r o m S L E E P M o d e o r

I D L E M o d e C o n t r o l ( f o r H X T o n l y )

f L

System Clock Configurations

HT66F016 Datasheet(PDF) 30 Page - Holtek Semiconductor Inc

HT66F016 Datasheet(HTML) 30 Page - Holtek Semiconductor Inc

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