BU9796FS Datasheet, PDF (7/12 Pages) Rohm – LCD Segment Driver series 80-segment Drivers (20SEG×4COM)

BU9796FS
Technical Note
●Cautions in Power ON/OFF
This device has “P.O.R” (Power-On Reset) circuit and Software Reset function.
Please keep the following recommended Power-On conditions in order to power up properly.
Please set power up conditions to meet the recommended tR, tF, tOFF, and Vbot spec
below in order to ensure P.O.R operation
* It has to set TEST2=”L” to be valid in POR circuit.
VDD
tF
tR
tOFF
Vbot
Recommendation condition of tR, tF, tOFF, Vbot (Ta=25℃)
tR
tF
tOFF
Vbot
Less than
Less than
More than
Less than
1ms
1ms
100ms
0.1V
Fig. 4 Power ON/OFF waveform
If it is difficult to meet above conditions, execute the following sequence after Power-On.
* It has to keep the following sequence in the case of TEST2=”H”. As POR circuit is invalid status.
But it is not able to accept Command input in Power off status, it has to take care that software reset is not
perfectly alternative method of POR function.
(1) Generate STOP condition
VDD
SDA
SCL
STOP condition
Fig. 5 Stop condition
(2) Generate START condition.
(3) Issue slave address
(4) Execute Software Reset (ICSET) command
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7/11
2009.05 - Rev.A