HT48R52/HT48R53

Rev. 1.20

17

December 6, 2005

the pull-high resistor is absent. It should be noted that a

non-pull-high I/O line operating in input mode will cause

a floating state.

Low Voltage Reset

- LVR

The microcontroller provides a low voltage reset circuit

in order to monitor the supply voltage of the device. If the

supply voltage of the device is within the range

tomatically reset the device internally.

The LVR includes the following specifications:

original state for more than 1ms. If the low voltage

state does not exceed 1ms, the LVR will ignore it and

do not perform a reset function.

²OR² function with the external

RES signal to perform a chip reset.

Note:

tion at 4MHz system clock.

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 has to be maintained for more than 1ms, therefore a 1ms delay is provided before

entering the reset mode.

5 . 5 V

3 . 0 V

2 . 2 V

0 . 9 V

5 . 5 V

Options

The following table shows all kinds of options in the microcontroller. All of the options must be defined to ensure having

a proper functioning system.

Items

Options

1

PA7~PA0 bit wake-up enable or disable (by bit)

2

PA, PB, PC, PD, PE pull-high enable or disable (by port)

3

4

WDT enable or disable

5

CLRWDT instructions: 1 or 2 instructions

6

7

PB0, PB1: normal I/O or Buzzer function

8

9

LVR enable or disable