LC75893M View Datasheet(PDF) - SANYO -> Panasonic
Part Name
Description
Manufacturer
LC75893M Datasheet PDF : 23 Pages
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LC75893M
Notes on the controller key data read techniques
1. Timer based key data acquisition
• Flowchart
CE = [L]
DO = [L]
• Timing chart
t3·······Key scan execution time when the key data agreed for two key scans (420T[s]).
t4·······Key scan execution time when the key data did not agree for two key scans and the key scan was executed again (840T[s]).
t5·······Key address (43H) transfer time
t6·······Key data read time
1
T = ——
fosc
• Explanation
In this technique, the controller uses a timer to determine key on/off states and read the key data. The controller must
check the DO state when CE is low every t7 period without fail. If DO is low, the controller recognizes that a key
has been pressed and executes the key data read operation.
The period t7 in this technique must satisfy the following condition.
t7 > (t5 + t6 + t4)
If a key data read operation is executed when DO is high, the read key data (KD1 to KD20) and sleep acknowledge
data (SA) will be invalid.
No. 5971-21/23
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