pcf2119x-2 NXP Semiconductors, pcf2119x-2 Datasheet - Page 6

• Manufacturer Part Number: pcf2119x-2
• Description: Controllers/drivers
• Manufacturer: NXP Semiconductors

Philips Semiconductors
7
7.1
The LCD supply voltage may be generated on-chip.
The voltage generator is controlled by two internal 6-bit
registers: V
at room temperature is given by the relationship:
7.2
Programmed value: 1 to 63. Voltage: 1.90 to 6.86 V.
T
Values producing more than 6.5 V at operating
temperature are not allowed. Operation above this
voltage may damage the device. When programming the
operating voltage the V
be taken into account.
Values below 2.2 V are below the specified operating
range of the chip and are therefore not allowed.
Value 0 for V
(i.e. V
Usually register V
character mode and register V
mode.
Table 2 Bias levels as a function of multiplex rate
Note
1. The values in the above table are given relative to V
28. August 2000
MULTIPLEX
ref
V
LCD controllers/drivers
OP(nom)
= 27 C.
FUNCTIONAL DESCRIPTION
1 : 18
RATE
1 : 9
1 : 2
A
LCD supply voltage generator
Programming ranges
= 0 in character mode, V
A
=
A
and V
and V
integer value of register 0.08
OF LEVELS
NUMBER
A
B
is programmed with the voltage for
. The nominal LCD operating voltage
B
5
5
4
switches the generator off
LCD
temperature coefficient must
B
with the voltage for icon
B
= 0 in icon mode).
V
V
V
V
op
op
op
1
+
3/4
1.82
3/4
2/3
V
2
(1)
op
6
V
When V
decoupled to V
V
compensated. When the voltage generator and the direct
mode are switched off, an external voltage may be
supplied at connected pads V
or lower than V
During direct mode (program DM register bit) the internal
voltage generator is turned off and the V
is directly connected to V
consumption during icon mode and Mux 1 : 9 (depending
on V
The LCD supply voltage generator ensures that, as long as
V
voltage V
7.3
The intermediate bias voltages for the LCD display are
also generated on-chip. This removes the need for an
external resistive bias chain and significantly reduces the
system current consumption. The optimum value of V
depends on the multiplex rate, the LCD threshold voltage
(V
scheme for 1 : 18 maximum rate allows V
most LCD liquids. The intermediate bias levels for the
different multiplex rates are shown in Table 2. These bias
levels are automatically set to the given values when
switching to the corresponding multiplex rate.
ss
LCD
DD
th
, e.g. 3/4 means 3/4
) and the number of bias levels. Using a 5-level bias
1/2
1/2
2/3
is in the valid range (2.2 to 4 V), the required peak
V
DD2
is independent of V
3
LCD bias voltage generator
LCD
value and LCD liquid properties).
OP
is generated on-chip the V
= 6.5 V can be generated at any time.
SS
DD
with a suitable capacitor. The generated
.
1/2
1/2
1/3
V
4
DD
(V
DD2
op
and is temperature
. This reduces the current
LCD1,2
V
ss
1/4
1/4
1/3
V
. V
).
5
PCF2119x-2
Product specification
LCD1,2
LCD
LCD
LCD
pads should be
output voltage
may be higher
< 5 V for
V
V
V
V
ss
ss
ss
6
LCD