NXP Semiconductors
PCF85133
Universal LCD driver for low multiplex rates
7.4.4 1:4 multiplex drive mode
When four backplanes are provided in the LCD, the 1:4 multiplex drive mode applies as
shown in Figure 8.
PCF85133_1
Product data sheet
BP0
BP1
BP2
BP3
Sn
Sn+1
Sn+2
Sn+3
state 1
state 2
VLCD
2VLCD / 3
VLCD / 3
VSS
VLCD
2VLCD / 3
VLCD / 3
VSS
VLCD
2VLCD / 3
VLCD / 3
VSS
VLCD
2VLCD / 3
VLCD / 3
VSS
VLCD
2VLCD / 3
VLCD / 3
VSS
VLCD
2VLCD / 3
VLCD / 3
VSS
VLCD
2VLCD / 3
VLCD / 3
VSS
VLCD
2VLCD / 3
VLCD / 3
VSS
VLCD
2VLCD / 3
VLCD / 3
0V
−VLCD / 3
−2VLCD / 3
−VLCD
VLCD
2VLCD / 3
VLCD / 3
0V
−VLCD / 3
−2VLCD / 3
−VLCD
Tfr
(a) Waveforms at driver.
(b) Resultant waveforms
at LCD segment.
Fig 8.
Vstate1(t) = VSn(t) − VBP0(t).
Von(RMS) = 0.577VLCD.
Vstate2(t) = VSn(t) − VBP1(t).
Voff(RMS) = 0.333VLCD.
Waveforms for the 1:4 multiplex drive mode with 1⁄3 bias
LCD segments
state 1
state 2
mgl749
Rev. 1 — 17 February 2009
© NXP B.V. 2009. All rights reserved.
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