HT69F30A Datasheet, PDF (52/202 Pages) Holtek Semiconductor Inc – TinyPowerTM I/O Flash 8-Bit MCU with LCD & EEPROM

HT69F30A/HT69F40A/HT69F50A
TinyPower^TM I/O Flash 8-Bit MCU with LCD & EEPROM
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.
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 Interrupts. 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
External Crystal
External RC
External Clock
Internal High Speed RC
External Low Speed Crystal
Internal Low Speed RC
Name
Freq.
HXT
ERC
400kHz~16MHz
8MHz
EC
400kHz~20MHz
HIRC
LXT
4, 8 or 12MHz
32.768kHz
LIRC
32kHz
Oscillator Types
Pins
OSC1/OSC2
OSC1
OSC1
—
XT1/XT2
—
System Clock Configurations
There are five methods of generating the system clock, three high speed oscillators and two low
speed oscillators. The high speed oscillators are is the external crystal/ceramic oscillator, external
RC network oscillator and the internal 4MHz, 8MHz or 12MHz RC oscillator. The two low speed
oscillators are the internal 32kHz RC oscillator and the external 32.768kHz crystal oscillator.
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.
Rev. 1.00
52
March 19, 2013