BU9799KV Datasheet, PDF (20/28 Pages) Rohm – Standard LCD Segment Driver

BU9799KV MAX 200 segments (SEG50×COM4)
●Cautions in Power ON/OFF
○Power supply sequence
Please keep Power ON/OFF sequence as below waveform.
To prevent incorrect display, malfunction and abnormal current,
VDD must be turned on before VLCD In power up sequence.
VDD must be turned off after VLCD In power down sequence.
Please satisfies VLCD≥VDD, t1>0ns, t2>0ns
t1
t2
VLCD
VDD
10%
VDD min
10%
VDD min
Datasheet
Figure 20. 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
Recommended condition of tR, tF, tOFF, Vbot (Ta=25℃)
tR
tF
tOFF
Vbot
Less than Less than More than Less than
5ms
5ms
20ms
0.3V
Figure 21. 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
Figure 22. Stop condition
(2) Generate STOP condition
(3) Generate START condition
(4) Issue slave address
(5) Execute ICSET command (Software reset).
Refer to the item of the ICSET command for the details.
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