BU91799KV-M Datasheet, PDF (20/29 Pages) Rohm – Low Duty LCD Segment Driver for Automotive Application

BU91799KV-M MAX 200 segments (SEG50×COM4)
Cautions in Power ON/OFF
Power Supply Sequence
To prevent incorrect display, malfunction and abnormal current, follow Power On/Off sequence shown in waveform below.
VDD must be turned on before VLCD during power up sequence.
VDD must be turned off after VLCD during power down sequence.
Set t1>0ns and t2>0ns.
t1
t2
VLCD
VDD
10%
VDD min
10%
VDD min
Figure 21. Power Supply Sequence
Caution in P.O.R Circuit Use
BU91799KV-M has “P.O.R” (Power-On Reset) circuit and Software Reset function.
Keep the following recommended Power-On conditions in order to power up properly.
Set power up conditions to meet the recommended tR, tF, tOFF, and Vbot specification below in order to ensure P.O.R
operation.
Set pin TEST1=”L” to enable POR circuit.
VDD
tF
tR
tOFF
Vbot
Recommended condition of tR, tF, tOFF, Vbot (Ta=25°C)
tR^(Note)
tF^(Note)
tOFF^(Note) Vbot^(Note)
1ms
to 500ms
1ms
to 500ms
Min 20ms
Less than
0.1V
(Note) This function is guaranteed by design, not tested in production process.
Figure 22. Power ON/OFF Waveform
If it is difficult to keep above conditions, execute the following sequence as quickly as possible after Power-On.
Setting TEST1="H" disables the POR circuit, in such case, execute the following sequence.
Note however that it cannot accept command while supply is unstable or below the minimum supply range.
Note also that software reset is not a complete alternative to POR function.
1. Generate STOP Condition
VDD
SDA
SCL
2. Generate START Condition
STOP condition
Figure 23. Stop Condition
VDD
SDA
SCL
START condition
Figure 24. Start Condition
3. Issue Slave Address
4. Execute Software Reset (ICSET) Command
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TSZ02201-0P4P0D301050-1-2
8. Feb. 2016 Rev.001