pcf8548 NXP Semiconductors, pcf8548 Datasheet - Page 20

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

Philips Semiconductors
Table 4 Programming the required bias system
Table 5 LCD bias voltage
12.10 Set V
The voltage at reference temperature can be calculated
as: [V
The operating voltage V
The generated voltage is dependent on the temperature,
programmed Temperature Coefficient (TC) and the
programmed voltage at reference temperature (T
Table 6 Typical values for parameters for the HV-generator programming
1999 Aug 16
V
V
a
a
b
T
SYMBOL
LCD
LCD
1
2
cut
65
V1
V2
V3
V4
V5
V6
LCD
Tcut
BS[2]
=
SYMBOL
0
0
0
0
1
1
1
1
a
(T = T
102 pixels matrix LCD driver
=
+
OP
V
a
OP
BIAS VOLTAGES
+
value
cut
V
(n + 3)/(n + 4)
(n + 2)/(n + 4)
)]
OP
b
2/(n + 4)
1/(n + 4)
V
V
LCD
b
LCD
SS
BS[1]
1
0
0
1
1
0
0
1
1
+
can be set by software.
T T
–
cut
8
7
2
1
BITS
BIAS VOLTAGES
9
9
9
9
FOR
TC
V
V
V
V
LCD
LCD
LCD
LCD
BS[0]
V
V
0
1
0
1
0
1
0
1
1
LCD
SS
9
BIAS
cut
).
2.94 (PRS = 0)
6.75 (PRS = 1)
0.03
27
(1)
(2)
20
The parameters are explained in Fig.16 and Table 6.
The maximum voltage that can be generated is dependent
on the V
Two overlapping V
command ‘HV-gen control’. For the LOW (PRS = 0) range
a = a
equal to b in both ranges. It should be noted that the
charge pump is turned off if V
to zero. For Mux 1 : 65 the optimum operation voltage of
the liquid can be calculated as follows:
where V
material used.
V
LCD
n
7
6
5
4
3
2
1
0
1
VALUE
and for the HIGH (PRS = 1) range a = a
=
th
DD2
-------------------------------------- -
is the threshold voltage of the liquid crystal
2
voltage and the display load current.
1
+
1
–
65
LCD
----------
RECOMMENDED MUX RATE
1
65
ranges are selectable via the
V
V
V
V
th
OP
C
=
[6;0] and bit PRS are all set
1 : 100
1 : 81
1 : 64
1 : 49
1 : 36
1 : 24
1 : 16
6.85 V
1 : 9
Product specification
UNIT
th
PCF8548
2
with steps