HT48RB8 datasheet(18/45 Pages) HOLTEK

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HT48RB8

Rev. 1.30

February 10, 2003

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~V

LVR) 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.

The relationship between VDD and VLVR is shown below.

Note:

VOPR is the voltage range for proper chip opera-

tion at 4MHz system clock.

5 . 5 V

3 . 3 V

3 . 0 V

0 . 9 V

V D D

V O P R

V L V R

5 . 5 V

V D D

5 . 5 V

V L V R

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 in its original state and exceed 1ms, therefore 1ms delay enters the

reset mode.

HT48RB8 Datasheet(PDF) 18 Page - Holtek Semiconductor Inc

HT48RB8 Datasheet(HTML) 18 Page - Holtek Semiconductor Inc

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