pcf8548 NXP Semiconductors, pcf8548 Datasheet - Page 19

• Manufacturer Part Number: pcf8548
• Description: 65 X 102 Pixels Matrix Lcd Driver
• Manufacturer: NXP Semiconductors

Philips Semiconductors
12.6
The X address points to the columns. The range of X is
0 to 101 (65H).
12.7
12.7.1
The PCF8548 incorporates a software configurable
voltage multiplier. After reset the voltage multiplier is set to
2
command ‘set HV-gen stages’ (see Tables 1 and 2).
12.8
Due to the temperature dependency of the liquid crystals
viscosity, the LCD controlling voltage V
increased with lower temperature to maintain optimum
contrast.
1999 Aug 16
65
V
DD2
Set X address of RAM
Set HV generator stages
Temperature control
. Other voltage multiplier factors are set via the
S[1:0]
102 pixels matrix LCD driver
handbook, halfpage
V LCD
LCD
Fig.15 Temperature coefficients.
must be
19
T cut
There are 4 different temperature coefficients available in
the PCF8548 (see Fig.15). The coefficients are selected
by the two bits TC[1:0]. Table 6 shows the typical values of
the different temperature coefficients. The coefficients are
proportional to the programmed V
12.9
The Bias voltage levels are set in the ratio
of R
The resulting bias levels are shown in Table 5.
Different multiplex rates require different factors n (see
Table 4); this is programmed by BS[2 : 0]. For Mux 1 : 65
the optimum bias value n is given by:
n
=
R
m 3
Bias system
–
nR
=
MGS402
T
R
65 3
–
R giving a
=
5.06
------------ -
n
=
1
+
LCD
5
4
Product specification
resulting in
.
bias system.
PCF8548
1
9
bias.