Philips Semiconductors
Universal LCD driver for low multiplex
rates
Product specification
OM4085
handbook, full pagewidth
BP0
BP1
BP2
Sn
Sn + 1
Sn + 2
VDD
VDD − Vop/3
VDD − 2Vop/3
VLCD
VDD
VDD − Vop/3
VDD − 2Vop/3
VLCD
VDD
VDD − Vop/3
VDD − 2Vop/3
VLCD
VDD
VDD − Vop/3
VDD − 2Vop/3
VLCD
VDD
VDD − Vop/3
VDD − 2Vop/3
VLCD
VDD
VDD − Vop/3
VDD − 2Vop/3
VLCD
state 1
Vop
2Vop/3
Vop/3
0
−Vop/3
−2Vop/3
−Vop
state 2
Vop
2Vop/3
Vop/3
0
−Vop/3
−2Vop/3
−Vop
Tframe
LCD segments
state 1
state 2
(a) waveforms at driver
(b) resultant waveforms
at LCD segment
At any instant (t):
Vstate 1(t) = VSn(t) − VBP0(t)
Von(rms) = Vop√33 = 0.638Vop
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Vstate 2(t) = VSn(t) − VBP1(t)
Voff(rms) = Vop = 0.333Vop
3
MGG395
1997 Feb 25
Fig.7 Waveforms for 1 : 3 multiplex drive mode: Vop = VDD − VLCD.
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