BU97931FV Datasheet, PDF (23/32 Pages) Rohm – Multifunction LCD Segment Driver

BU97931FV MAX 112 segments (SEG28×COM4)
●Cautions on Power-On/ Power-Off condition
○POR circuit
BU97931FV 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 properly, please satisfy
Vbot lower than 0.5V condition.)
VDD
VDET
tR
tOFF
Vbot
Figure 17. Power ON/OFF Waveform
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
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 Software reset 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