HT46R0664 datasheet(27/92 Pages) HOLTEK

27 / 92 page

Rev. 1.00

�6

��st 1�� 011

Rev. 1.00

�7

��st 1�� 011

HT46R0664

Enhanced A/D+LCD 8-Bit OTP MCU

Oscillator

Various oscillator options offer the user a wide range of functions according to their various

application requirements. The flexible features of the oscillator functions ensure that the best

optimisation can be achieved in terms of speed and power saving.

Oscillator Overview

In addition to being the source of the main system clock the oscillators also provide clock sources

for the Watchdog Timer and Time Base functions. External oscillators 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 requirements, while the opposite

is of course true for the lower frequency oscillators. With the capability of dynamically switching

between fast and slow system clock, the device has the flexibility to optimize the performance/power

ratio, a feature especially important in power sensitive portable applications.

Type

Name

Freq.

Pins

External Crystal

HXT

400kHz~1�MHz

OSC1/OSC�

External RC

ERC

400kHz~1�MHz

OSC1

Internal Hi�h Speed RC

HIRC

4� 8 or 1�MHz

—

External Low Speed RC

LXT

3�768Hz

XT1/XT�

Internal Low Speed RC

LIRC

3�kHz

—

Oscillator Types

System Clock Configurations

There are five system oscillators, three high speed oscillators and two low speed oscillators. The

high speed oscillators are the external crystal/ceramic oscillator – HXT, the external – ERC,

and the internal RC oscillator – HIRC. The one low speed oscillator is the external 32768Hz

oscillator – LXT and the internal 32kHz (VDD=5V) oscillator – LIRC.

External Crystal/Resonator Oscillator – HXT

The simple connection of a crystal across OSC1 and OSC2 will create the necessary phase shift and

feedback for oscillation. However, for some crystals and most resonator types, to ensure oscillation

and accurate frequency generation, it is necessary to add two small value external capacitors, C1 and

C2. The exact values of C1 and C2 should be selected in consultation with the crystal or resonator

manufacturer’s specification.

OS C1

OS C2

To i nt er na l

ci rc ui ts

In te rn al

O sc illa to r

Ci rc ui t

No te :1 . Rp i s no rm a lly n o t r equ ir ed . C 1 and C2 a re r equi r ed.

2. A lt hough n o t s how n OS C1 /O SC 2 pi ns hav e a par as it ic

c apac it anc e of a ro u nd 7pF .

Crystal/Resonator Oscillator – HXT

HT46R0664 Datasheet(PDF) 27 Page - Holtek Semiconductor Inc

HT46R0664 Datasheet(HTML) 27 Page - Holtek Semiconductor Inc

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

Datasheet Download

Link URL