BU9795AKV Datasheet, PDF (13/16 Pages) Rohm – Standard function Segment Drivers

BU9795AKV, BU9795AFV, BU9795AGUW
Technical Note
● Notes for Application (BU9795AKV /BU9795AFV / BU9795AGUW)
In case, BU9795AKV/ BU9795AFV/ BU9795AGUW used at VLCD≠VSS, voltage gap occur between SEG line to COM1 – 3
line at Display off state. Because of this voltage gap, there is possibility to display LCD for a moment.
To avoid this phenomenon, please decide VDD and VLCD level to satisfy Voff voltage lower than OFF level (OFF level = 1V at
the example explained below).
condition ： VDD=5.0V
VLCD=2.0V
1/3bias
DDRAM data ALL "H"
Frame inversion
In case, VLCD voltage different from VSS level（VLCD≠VSS)
In this case, volatage gap occur, between SEG line to COM 1-3 line.
Because of this gap, there is possibility to display LCD for a moment.
1Frame
Send "Display off" command
VDD (5V)
SEG0 Output
VLCD (2V)
VSS
VLCD-VSS=2V
Output VLCD level at display off
（All SEG terminal）
COM0 Output
VDD (5V)
VLCD (2V)
VSS
VLCD-VSS=2V
COM1 Output VDD (5V)
Output VLCD level at display off
（Only COM0 terminal）
VLCD (2V)
VSS
VLCD-VSS=2V
Output VSS level at display off
(at COM 1-3 terminal)
Voltage gap of
COM0-SEG0
3V
2V
1V
0V
-1V
-2V
-3V
Voltage gap of
COM1-SEG0
3V
2V
1V
0V
-1V
-2V
-3V
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Display on
Display off
the volatage between COM0 to SEG0
is 0V at display off.
Display on
ON level
OFF level
Display off
the volatage between COM1 to SEG0
is -2V at display off.
Voff
13/15
Voltage gap occur between COM1 to SEG0 at display off.
So, there is possibility to display LCD.
（Only at COM 1-3 line）
2009.07 - Rev.B