lc75864w Sanyo Semiconductor Corporation, lc75864w Datasheet - Page 12

• Manufacturer Part Number: lc75864w
• Description: 1/4 Duty Lcd Display Drivers With Key Input Function
• Manufacturer: Sanyo Semiconductor Corporation

Sleep Mode Functions
Sleep mode is set up by setting S0 or S1 in the control data to 1. The segment outputs will all go low and the common
outputs will also go low, and the oscillator on the OSC pin will stop (it will be started by a key press). This reduces
power dissipation. This mode is cleared by sending control data with both S0 and S1 set to 0. However, note that the
S1/P1 to S4/P4 outputs can be used as general-purpose output ports according to the state of the P0 to P2 control data
bits, even in sleep mode. (See the control data description for details.)
Key Scan Operation Functions
1. Key scan timing
2. In normal mode
The key scan period is 384 T (s). To reliably determine the on/off state of the keys, the LC75864E/W 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) 800 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 LC75864E/W cannot detect a key press shorter than 800 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
• The pins KS1 to KS6 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
• If a key is pressed for longer than 800 T (s) (where T =
• After the controller reads the key data, the key data read request is cleared (DO is set high) and the LC75864E/W
presses are recognized by determining whether multiple key data bits are set.
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.
performs another key scan. Also note that DO, being an open-drain output, requires a pull-up resistor (between 1
and 10 k ).
KS1
KS2
KS3
KS4
KS5
KS6
from pins that are set low.
*3
*3
*3
*3
*3
Key on
1
2
3
4
5
LC75864E, 75864W
768T (s)
6
1
f
OSC
1
2
) the LC75864E/W outputs a key data read request (a
3
4
5
6
*3
*3
*3
*3
*3
T =
No. 6860-12/26
fosc
1