BU9794KV Datasheet, PDF (19/23 Pages) Rohm – For 200 Segment type LCD LCD Segment Driver

● Cautions in Power ON/OFF (BU9799KV)
○ Power supply sequence
Please keep Power ON/OFF sequence as below waveform.
VLCD
VDD
Fig. BU9799KV-4 Power supply sequence
○ Caution in P.O.R circuit use
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 TEST1=”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 5ms Less than 5ms More than Less than 0.3V
20ms
Fig. BU9799KV-5 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 TEST1=”H”. As POR circuit is
invalid status.
(1) TEST1 =”H”
VDD
SDA
SCL
STOP condition
Fig. BU9799KV-6 Stop condition
(2) After send STOP condition, execute Software Reset (ICSET) command.
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