HT48R70A-1(2004) 데이터 시트보기 (PDF) - Holtek Semiconductor

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HT48R70A-1
(Rev.:2004)

I/O Type 8-Bit MCU

Holtek Semiconductor 

Low Voltage Reset - LVR

The microcontroller provides 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

0.9V~VLVR, such as changing a battery, the LVR will au-

tomatically reset the device internally.

The LVR includes the following specifications:

· The low voltage (0.9V~VLVR) has to remain in their

original state to exceed 1ms. If the low voltage state

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

perform a reset function.

· The LVR uses the ²OR² function with the external

RES signal to perform chip reset.

V DD

5 .5 V

HT48R70A-1/HT48C70-1

The relationship between VDD and VLVR is shown below.

V DD

V O PR

5 .5 V 5 .5 V

V LV R

3 .0 V

2 .2 V

Note:

0 .9 V

VOPR is the voltage range for proper chip opera-

tion at 4MHz system clock.

V LV R

0 .9 V

0V

R e s e t S ig n a l

L V R D e te c t V o lta g e

R eset

N o r m a l O p e r a tio n

R eset

*1

*2

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 in its original state and exceed 1ms, therefore 1ms

delay enters the reset mode.

Options

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

system functioning.

No.

Options

1

WDT clock source: WDT oscillator or fSYS/4 or RTC oscillator or disable

2

CLRWDT instructions: 1 or 2 instructions

3

Timer/Event Counter 0 clock sources: fSYS/4 or RTCOSC

4

Timer/Event Counter 1 clock sources: fSYS/4 or RTCOSC

5

PA bit wake-up enable or disable

6

PA CMOS or Schmitt input

7

PA, PB, PC, PD, PE, PF, PG pull-high enable or disable (By port)

8

System oscillator

Ext. RC, Ext. crystal, Int. RC+RTC

9

Int. RC frequency selection 3.2MHz, 1.6MHz, 800kHz or 400kHz

10 LVR enable or disable

Rev. 1.60

19

June 9, 2004

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