HT82K95EE datasheet(17/45 Pages) HOLTEK

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HT82K95EE/HT82K95AE

Rev. 1.20

August 28, 2006

Low Voltage Reset

- LVR

The microcontroller contains a low voltage reset circuit

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

supply voltage of the device drops to within a range of

0.9V~VLVR such as might occur when changing the bat-

tery, the LVR will automatically reset the device inter-

nally.

The LVR includes the following specifications:

· For a valid LVR signal, a low voltage i.e. a voltage in

the range between 0.9V~VLVR must exist for greater

than 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 for over 1ms in its original state, therefore there

¢s a 1ms delay

before entering the reset mode

HT82K95EE Datasheet(PDF) 17 Page - Holtek Semiconductor Inc

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