LC75893M View Datasheet(PDF) - SANYO -> Panasonic

Part Name

Description

Manufacturer

LC75893M

1/3 Duty LCD Display Driver with Key Input Function

SANYO -> Panasonic 

LC75893M

Key Scan Operation Functions

1. Key scan timing

The key scan period is 192 T (s). To reliably determine the on/off state of the keys, the LC75893M scans the keys

twice and determines that a key has been pressed when the key data agrees. It outputs a key data read request (a low

level on DO) 420 T (s) after starting a key scan. If the key data does not agree and a key was pressed at that point, it

scans the keys again. Thus the LC75893M cannot detect a key press shorter than 420 T (s).

Note: *3. In sleep mode the high/low state of these pins is determined by the S0 and S1 bits in the control data. Key scan output signals are not output

from pins that are set low.

2. In normal mode

• The pins KS1 to KS4 are set high.

• When a key is pressed a key scan is started and the keys are scanned until all keys are released. Multiple key

presses are recognized by determining whether multiple key data bits are set.

• If a key is pressed for longer than 420 T (s) (where T = 1 ) the LC75893M output a key data read

fOSC

request (a low level on DO) to the controller. The controller acknowledges this request and reads the key data.

However, if CE is high during a serial data transfer, DO will be set high.

• After the controller reads the key data, the key data read request is cleared (DO is set high) and the LC75893M

performs another key scan. Also note that DO, being an open-drain output, requires a pull-up resistor (between 1

and 10 kΩ).

No. 5971-11/23

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