PCF8566
NXP Semiconductors
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
PCF8566 allows the use of 1⁄2 bias or 1⁄3 bias (see Figure 6 and Figure 7).
T
fr
V
LCD
LCD segments
V
V
/ 2
/ 2
BP0
BP1
Sn
LCD
SS
state 1
state 2
V
LCD
V
V
LCD
SS
V
LCD
V
V
SS
LCD
Sn+1
V
SS
(a) Waveforms at driver.
V
V
LCD
/ 2
LCD
0 V
−V
state 1
/ 2
LCD
−V
LCD
V
V
LCD
/ 2
LCD
0 V
state 2
−V
/ 2
LCD
LCD
−V
(b) Resultant waveforms
at LCD segment.
mgl746
Vstate1(t) = VSn(t) − VBP0(t).
Von(RMS) = 0.791VLCD
.
Vstate2(t) = VSn(t) − VBP1(t).
Voff(RMS) = 0.354VLCD
Fig 6. Waveforms for the 1:2 multiplex drive mode with 1⁄2 bias
PCF8566_7
© NXP B.V. 2009. All rights reserved.
Product data sheet
Rev. 07 — 25 February 2009
11 of 48
NXP [ NXP ]
