NJU6535 데이터 시트보기 (PDF) - Japan Radio Corporation

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NJU6535

1/3 , 1/4 Duty LCD Driver

Japan Radio Corporation  

NJU6535

(5) Power save mode

Power save mode 1 to 3 is set by “1” level as a control data in PS0 or 1, and released by “0” in PS0 and PS1.

In power save mode, segment drivers and commons output “L” level and the internal oscillation circuit is stop

the operation ( but operates at Key in detection) for operation current reduction.

However, output terminals SEG1/P0 to SEG4/P3 operate as General output port set by control data P0 and

P1 in power save mode. (refer (1)Instruction (e)Segment output / General output port)

(6) Key scan circuit

Key scan circuit connects the 6 x 5 key-matrix maximum and reads the data of 30 keys maximum. It chooses

the number of keys in key-matrix by “Segment output / key scan output select” instruction.

It outputs a identified key data to CPU after comparison with two data read from the key-matrix in twice for

reliable key operation. If those data are not identified, key data is not outputted. It outputs “L” signal through

“SO” terminal as the request after 577T[s] (T=1/fosc) when any key is operated. Furthermore, the key scan

circuit structures for reducing the external components like as Diodes to prevent circuit short problem.

(6-1) The relation between output data and key matrix

The relation between output data and key matrix shows bellow table and sets “1” signal for operated key.

In case of 20 keys application, unassigned area for keys from KD1 to KD10 in bellow table take “0” signal. In

case of 25 keys application, unassigned area from KD1 to KD5 take “0” signal also.

In mode of Power save 1, area for keys from KD1 to KD25 in bellow table take “0” signal. In mode of Power

save 2, area from KD1 to KD20 take “0” signal also. The terminals, which are not connected any keys, should be open.

K0

K1

K2

K3

K4

S0

KD1

KD2

KD3

KD4

KD5

S1

KD6

KD7

KD8

KD9

KD10

S2

KD11

KD12

KD13

KD14

KD15

S3

KD16

KD17

KD18

KD19

KD20

S4

KD21

KD22

KD23

KD24

KD25

S5

KD26

KD27

KD28

KD29

KD30

(6-2) Data output timing

The data output format shows bellow. The data output mode is set by “L” status of SCL terminal at the rising

signal of CE terminal.

CE

SCL

SI

SO

* KD1 KD2

Key data

KD29 KD30 PSF

(6-3) Power save flag(PSF)

The status of Power save flag is outputted after KD30 in Key data reading. This flag sets “1” signal in mode of

Power save in Key data reading and sets “0” in mode of Normal.

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