NJU6535 데이터 시트보기 (PDF) - Japan Radio Corporation

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NJU6535

1/3 , 1/4 Duty LCD Driver

Japan Radio Corporation  

NJU6535

(7) Power on reset circuit initializes

Power on reset circuit initializes the NJU6535 at Power ON and OFF. It generates reset signal to

initialize the system at low VDD less than power down detection voltage (2.5V typical).

(7-1) Initial status in reset

1, Stop the oscillation circuit

2, Display Off (Available Serial data transmission)

3, Disable Key scan function

4, Filled “L” data in all of key data buffer

(7-2) The status of output port terminals in power on reset

Output terminals

SEG1/P0 to SEG4/P3

SEG5 to SEG39

SEG40/COM4

COM1 to COM3

S0/SEG41,S1/SEG42

S2 to S4

S5

SO

Reset status

L *1

L

L *1

L

L *1

X *2

H

H *3

*1 This terminal operates as segment driver and outputs “L”.

*2 This terminal is not fixed the function in/after power on reset until PS0 and PS1 of control data are transmitted.

*3 This terminal consisted of Open-drain output type circuit requires external pull-up resister (1K ohm to 10k)

connect ting to external power source for CPU. I f key data read is executed in power on reset, the read data is

fixed as “H”.

(7-3) Power on reset operation

When the voltage rising time of power source is over than 1mS, the generated signal of VDET initializes

the system of NJU6535 as reset. When the voltage falling time of power source is over than 1mS, the

system is also reset. This status of reset is released automatically at the falling signal of CE terminal after

completed serial data transmission ( Display data D1 to D126 and control data at 1/3 duty, Display data

D1 to D164 and control data at 1/4 duty).

t1

t2

VDD

CE

Internal

data

VDET

Display control

data send

Not fixed

System reset time

Fixed

VDET VDD rising time

VDD falling time

t1>1[ms]

t2>1[ms]

When these voltage rising or falling time of power source are not over than 1ms, the Initialization

operaiton as reset does not operate correctly.

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