HT48R063 datasheet(27/94 Pages) HOLTEK

27 / 94 page

HT48R063/064/065/066/0662/067

Rev. 1.30

June 11, 2010

running but the WDT oscillator continues to free-run and

to keep the watchdog active. However, to preserve

power in certain applications the LIRC can be disabled

via a configuration option.

Operating Modes

By using the LXT low frequency oscillator in combina-

tion with a high frequency oscillator, the system can be

selected to operate in a number of different modes.

These Modes are Normal, Slow, Idle and Sleep.

Mode Types and Selection

The higher frequency oscillators provide higher perfor-

mance 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 oscillators,

the device has the flexibility to optimise the perfor-

mance/power ratio, a feature especially important in

power sensitive portable applications.

· HT48R063/HT48R064/HT48R065/HT48R066

For these devices, if the LXT oscillator is used then

the internal RC oscillator, HIRC, must be used as the

high frequency oscillator. If the HXT or the ERC oscil-

lator is chosen as the high frequency system clock

then the LXT oscillator cannot be used for sharing the

same pins. The CLKMOD bit in the CTRL0 register

can be used to switch the system clock from the high

speed HIRC oscillator to the low speed LXT oscillator.

When the HALT instruction is executed and the device

enters the Idle/Sleep Mode the LXT oscillator will al-

ways continue to run. For these devices the LXT crys-

tal is connected to the OSC1/OSC2 pins and LXT will

always run (the LXTEN bit is not used).

Note that CLKMOD is only valid in HIRC+LXT oscilla-

tor configuration for HT48R063/HT48R064/

HT48R065/HT48R066.

· HT48R0662/HT48R067

For these devices the LXT oscillator can run together

with any of the high speed oscillators, namely the

HXT, ERC or the HIRC. The CLKMOD bit in the

CTRL0 register can be used to switch the system

clock from the selected high speed oscillator to the

low speed LXT oscillator. When the HALT instruction

is executed the LXT oscillator can be chosen to run or

not using the LXTEN bit in the CTRL2 register.

For all devices, when the system enters the Sleep or

Idle Mode, the high frequency system clock will al-

ways stop running. The accompanying tables shows

the relationship between the CLKMOD bit, the HALT

instruction and the high/low frequency oscillators. The

CLMOD bit can change normal or Slow Mode.

· Operating Mode Control

¨ HT48R063/HT48R064/HT48R065/HT48R066

Operating

Mode

OSC1/OSC2 Configuration

HXT

ERC

HIRC

HIRC + LXT

HIRC

LXT

Normal

Run

Slow

¾¾¾

Stop

Run

Sleep

Stop

Run

²¾² unimplemented

¨ HT48R0662/HT48R067

Operating

Mode

OSC1/OSC2

Configuration

XT1/XT2

Configuration

HXT

ERC HIRC

LXT

LXTEN=0 LXTEN=1

Normal

Run

Slow

Stop

Run

Idle

Stop

Run

Sleep

Stop

H X T

E R C

H I R C

M U X

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

L X T

M U X

( S L O W )

( N o r m a l )

L I R C

M U X

T o w a t c h d o g t i m e r

f H X T

f E R C

f H I R C

f L X T

f L I R C

f S Y S

f S Y S / 4

C L K M O D

( D e t e r m i n e N o r m a l /

S l o w M o d e )

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

System Clock Configurations

HT48R063 Datasheet(PDF) 27 Page - Holtek Semiconductor Inc

HT48R063 Datasheet(HTML) 27 Page - Holtek Semiconductor Inc

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