BU97930MUV_15 Datasheet, PDF (23/32 Pages) Rohm – Multifunction LCD Segment Driver

BU97930MUV MAX 108 segments (SEG27×COM4)
●Cautions on Power-On/ Power-Off condition
○POR circuit
BU97930MUV has “P.O.R” (Power-On Reset) circuit and Software Reset function.
Please follow the recommended Power-On conditions in order to power up properly.
1, Please set power up conditions, follow the recommended tR, tF, tOFF, and Vbot specification below in order to
ensure P.O.R operation.
(*The detection voltage of POR varies because of environment, etc. To operate POR, please satisfy
Vbot lower than 0.5V condition.)
VDD
VDET
tR
tOFF
Vbot
Recommended condition of tR, tF, tOFF, Vbot
tR
tOFF
Vbot
VDET
less than
10ms
Over
1ms
less than
0.5V
TYP
1.2V
* VDET : POR detect level
Figure 17. Power ON/OFF Waveform
2, If it is difficult to meet the above conditions, execute the following sequence after Power-On.
(1) CSB=”L”→”H” condition
(2) After CSB”H”→“L”, execute SWRST command.
In addition, in order to the SWRST command certainly, please wait 1ms after a VDD level reaches to 90% and
CSB=”L”→”H”.
*Before SWRST command, input device will be in unstable state, since SWRST command does not operate
perfect substitution of a POR function.
VDD
CSB
Min 1ms
Min 50ns
SWRST
Command
Figure 18. SWRST Command Sequence
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10.Apr.2015 Rev.004