NXP Semiconductors
PCA85133
Universal LCD driver for low multiplex rates
7.4.2 1:2 Multiplex drive mode
When two backplanes are provided in the LCD, the 1:2 multiplex mode applies. The
PCA85133 allows the use of 1⁄2 bias or 1⁄3 bias in this mode as shown in Figure 5 and
Figure 6.
BP0
BP1
Sn
Sn+1
VLCD
VLCD/2
VSS
VLCD
VLCD/2
VSS
VLCD
VSS
VLCD
VSS
state 1
state 2
VLCD
VLCD/2
0V
−VLCD/2
−VLCD
VLCD
VLCD/2
0V
−VLCD/2
−VLCD
Tfr
LCD segments
state 1
state 2
(a) Waveforms at driver.
(b) Resultant waveforms
at LCD segment.
013aaa208
Fig 5.
Vstate1(t) = VSn(t) − VBP0(t).
Von(RMS) = 0.791VLCD.
Vstate2(t) = VSn(t) − VBP1(t).
Voff(RMS) = 0.354VLCD.
Waveforms for the 1:2 multiplex drive mode with 1⁄2 bias
PCA85133_1
Product data sheet
Rev. 1 — 23 October 2009
© NXP B.V. 2009. All rights reserved.
9 of 44