HT46R53/HT46R54

Rev. 1.40

21

July 12, 2005

Options

The following shows kinds of options in the device. ALL the options must be defined to ensure having a proper function-

ing system.

Options

OSC type selection.

This option is to decide if an RC or crystal oscillator is chosen as system clock.

WDT source selection.

There are three types of selection: on-chip RC oscillator, instruction clock or disable the WDT.

CLRWDT times selection.

This option defines how to clear the WDT by instruction.

²One time² means that the ²CLR WDT² instruction can clear

the WDT.

²Two times² means only if both of the ²CLR WDT1² and ²CLR WDT2² instructions have been executed,

then WDT can be cleared.

Wake-up selection.

This option defines the wake-up function activity. External I/O pins (PA only) all have the capability to wake-up the

chip from a HALT by a falling edge. (Bit option)

Pull-high selection.

This option is to decide whether a pull-high resistance is visible or not in the input mode of the I/O ports. PA is bit op-

tion; PB, PC and PD are port option.

PFD selection.

PA3: Level output or PFD output.

PWM selection: (7+1) or (6+2) mode

PD0: level output or PWM output

WDT time-out period selection.

There are four types of selection: WDT clock source divided by 2

LVR selection.

Enable or disable LVR function.

5 . 5 V

0 . 9 V

0 V

R e s e t S i g n a l

R e s e t

* 1

* 2

N o r m a l O p e r a t i o n

R e s e t

L V R D e t e c t V o l t a g e

Low Voltage Reset

Note:

*1: To make sure that the system oscillator has stabilized, the SST provides an extra delay of 1024 system

clock pulses before entering the normal operation.

*2: Since low voltage state has to be maintained in its original state for over 1ms, therefore after 1ms delay,

the device enters the reset mode.