HT46R064D/065D/066D
Enhanced A/D Type 8-Bit OTP MCU with LED Driver
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 selections and operation are selected through a
combination of configuration options and registers.
System 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 a two fully integrated internal oscillators, requiring no external components, are
provided to form a wide range of both fast and slow system oscillators.
Type
Name
HXT
Freq.
Pins
OSC1/OSC2
OSC1
External Crystal
400kHz~12MHz
400kHz~12MHz
4, 8 or 12MHz
32768Hz
External RC
ERC
HIRC
LXT
Internal High Speed RC
External Low Speed Crystal
Internal Low Speed RC
¾
OSC1/OSC2
¾
LIRC
13kHz
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 two low speed oscillator are the external 32768Hz oscillator --
LXT and the internal 13kHz (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.
Crystal/Resonator Oscillator - HXT
Rev. 1.00
27
January 12, 2011
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
