UPD16431A NEC, UPD16431A Datasheet - Page 8

• Manufacturer Part Number: UPD16431A
• Description: 1/2/ 1/3/ 1/4-DUTY LCD CONTROLLER/DRIVER
• Manufacturer: NEC

CONFIGURATION OF KEY DATA LATCH
significant bit. Key data is read once a frame and latched when coinciding with the immediadtely preceding
data. In other words, it requires at least 2 frames from the time the key is pressed till data is confirmed to
be the key data (the key request becoming H).
KEY INPUT EQUIVALENT CIRCUIT
8
The key data is latched as illustrated below and is read by a read command, starting from the most
The key data is 0 when off and 1 when on.
MSB
KS
8
• The pull-down control signal goes high only during key
• The on-resistance of the pull-down transistor is several k .
KS
source output and turns on the pull-down transistor.
Pull-down
control signal
7
To key latch
KS
6
32-bit latch/SHIFT register
KS
5
KS
4
KS
KEY
3
4
KEY
KS
2
3
KEY
KEY n
2
KS
KEY
1
1
LSB
PD16431A