PCF2119AU NXP [NXP Semiconductors], PCF2119AU Datasheet - Page 11

• Manufacturer Part Number: PCF2119AU
• Description: LCD controllers/drivers Single-chip LCD controller and driver
• Manufacturer: NXP [NXP Semiconductors]

NXP Semiconductors
PCF2119X
Product data sheet
8.5 LCD bias voltage generator
Remarks:
When the LCD supply voltage is generated on-chip, the V
V
temperature compensated.
In
to V
pump. The multiplication factor has to be set such, that V
multiplied with the programmed multiplication factor exceeds the required V
circumstances (i.e. at low temperatures and along with the temperature compensation -
see
(it is set by
consumption increases (see
When the V
be supplied at connected pins V
lower than V
In direct mode (see Icon_ctl instruction,
turned off and the V
current consumption depending on V
The V
to 4 V), the required peak voltage V
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
threshold voltage (V
1:18 multiplex rate allows V
The intermediate bias levels for the different multiplex rates are shown in
bias levels are automatically set to the given values when switching to the corresponding
multiplex rate.
SS
•
•
Equation 2
DD2
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 temperature coefficient of V
Values below 2.2 V are below the specified operating range of the chip and are
therefore not allowed.
Section
with a suitable capacitor. The generated V
LCD
and V
generator ensures that, as long as V
Equation
LCD
10.2.3.4). If still a higher multiplication factor is chosen, V
DD2
the internal charge pump is not considered. However, if the supplied voltage
DD3
All information provided in this document is subject to legal disclaimers.
generator and the direct mode are switched off, an external voltage may
.
is below the required V
LCDOUT
th
2) but the current that can be delivered will be higher. Also current
) and the number of bias levels. Using a 5-level bias scheme for the
Rev. 7 — 15 November 2010
output voltage is directly connected to V
LCD
Section
< 5 V for most LCD liquids.
LCDIN
LCD
16.6).
DD2
and V
= 6.5 V can be generated at any time.
Section
LCD
value and LCD liquid properties.
LCDOUT
it is necessary to use the internal charge
LCD
LCDOUT
DD2
10.2.3.3) the internal V
depends on the multiplex rate, the LCD
. V
and V
LCDIN
LCDOUT
is independent of V
DD3
LCD
DD2
and V
are in the valid range (2.2 V
pins should be decoupled to
must be taken into account.
and V
LCD controllers/drivers
LCDOUT
DD3
DD2
PCF2119x
LCD
. This reduces the
© NXP B.V. 2010. All rights reserved.
(which are equal)
LCD
may be higher or
will not increase
Table
DD
generator is
LCD
and is
6. These
under all
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