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V6118 View Datasheet(PDF) - EM Microelectronic - MARIN SA

Part Name
Description
MFG CO.
V6118
EMMICRO
EM Microelectronic - MARIN SA EMMICRO
V6118 Datasheet PDF : 15 Pages
1 2 3 4 5 6 7 8 9 10 Next Last
R
Functional Description
Supply Voltage VLCD, VDD, VSS
The voltage between VDD and VSS is the supply voltage for
the logic and the interface. The voltage between VLCD and
VSS is the supply voltage for the LCD and is used for the
generation of the internal LCD bias levels. The internal
LCD bias levels have a maximum impedance of 25 kfor
a VLCD voltage from 3 to 8V. Without external connections
to the V1, V2, V3 bias level inputs, the V6118 can drive
most medium sized LCD (pixel area up to 4'000 mm2).
For displays with a wide variation in pixel sizes, the
configuration shown in Fig. 13 can give enhanced contrast
by giving faster pixel switching times. On changing the
row polarity (see Fig. 7, 8 and 9) the parallel capacitors
lower the impedance of the bias level generation to the
peak current, giving faster pixel charge times and thus a
higher RMS "on" value. A higher RMS "on" value can
give better contrast. IF for a given LCD size and
operating voltage, the "off" pixels appear "on", or there is
poor contrast, then an external bias level generation
circuit can be used with the V6118. An external bias
generation circuit can lower the bias level impedance and
hence improve the LCD contrast (see Fig. 12). The
optimum values of R, Rx and C, vary according to the
LCD size used and VLCD. They are best determined
through actual experimentation with the LCD.
For LCD with very large average pixel area (eg. up to
10'000 mm2), the bias level configuration shown in Fig. 14
should be used.
When V6118s are cascaded, connect the V1, V2 and V3
bias inputs as shown in Fig. 10. The pixel load is
averaged across all the cascaded drivers. This will give
enhanced display contrast as the effective bias level
source impedance is the parallel combination of the total
number of drivers. For example, if two V6118 are
cascaded as shown in Fig. 10, then the maximum bias
level impedance becomes 12.5 kfor a VLCD voltage from
3 to 8V.
Table 8 shows the relationship between V1, V2 and V3 for
the multiplex rates 2, 4 and 8. Note that VLCD > V1 > V2 >
V3 for the V6118 2 and V6118 8, and for the V6118 4,
VLCD > V1 > V2.
Data Input /Output
The data input pin, DI, is used to load serial data into the
V6118. The serial data word length is 40 bits when COL
is inactive, and 48 bits when it is active. Data is loaded in
inverse numerical order, the data for bit 40 (bit 48 when
COL is active) loaded first with the data for bit 1 last. The
column data bits are loaded first and then the address bits
(see Fig. 4 & 5).
The data output pin, DO, is used in cascaded applications
(see Fig. 10). DO transfers the data to the next cascaded
chip. The data at DO is equal to the data at DI delayed by
40 clock periods, when COL is inactive and 48 clock
periods when COL is active. In order to cascade V6118s,
the DO of one chip must be connected to DI of the
following chip (see Fig. 10). In cascaded applications the
data for the last V6118 (the one that does not have DO
connected) must be loaded first and the data for the first
V6118 (its DI is connected to the processor) loaded last
(see Fig. 10).
The display RAM word length is 40 bits (see Fig. 6). Each
LCD row has a corresponding display RAM address which
provides the column data (on or off) when the row is
selected (on). When downloading data to the V6118, any
display selected RAM address can be chosen, there is no
Copyright © 2004, EM Microelectronic-Marin SA
V6118
display RAM addressing sequence (see Fig.4 & 5). The
same data can be written to more than one display RAM
address. I fmore than one address bit is set, then more
than one display RAM address is write enabled, and so
the same data is written to more the one address. This
feature can be useful to flash the LCD on and off under
software control. If the address bits are all zero then no
display RAM address is write enabled and no data is
written to the display RAM on the falling edge of STR. Use
address 0 to synchronize cascaded V6118s without
updating the display RAM.
CLK Input
The CLK input is used to clock the DI serial data into the
shift register and to clock the DO serial data out. Loading
and shifting of the data occurs at the falling edge of this
clock, outputting of the data at the rising edge (see Fig. 3).
When cascading devices, all CLK lines should be tied
together (see Fig. 10).
STR Input
The STR input is used to write to the display RAM, to
blank the LCD, and synchronize cascaded V6118. The
STR input writes the data loaded into the shift register, on
the DI input, to the display selected RAM on the falling
edge of the STR signal. The display RAM address is
given by the address bits (see Fig. 4 & 5)
The STR input when high blanks the LCD by
disconnecting the internal voltage bias generation from
the VSS potential. Segment outputs S1 to S40 (rows and
columns) are pulled up to VLCD. The delay to driving the
LCD with VLCD on S1 to S40, is dependent on the
capacitive load of the LCD and is typically 1 µs. An LCD
pixel responds to RMS voltage and takes approximately
100 ms to turn on or off. The delay from putting STR high
to the LCD being blank is dependent on the LCD off time
and is typically 100 ms. In applications which have a long
STR pulse width (10 µs) the LCD is driven by VLCD on both
the rows and columns during this time. As the time is
short (1 µs), it will have zero measurable effect on the
RMS "on" value (over 100 ms) of an LCD pixel and also
zero measurable effect on the pixel DC component. Such
STR pulses will not be visible to the human eye on an
LCD.
Note: if an external voltage bias generation circuit is
used as shown in Fig. 12 to 14, the LCD blank
function (STR high) will not blank the LCD. When STR
is high, the LCD will be driven by the parallel combination
of the external voltage bias generation circuit and part of
the internal voltage bias generation circuit.
The STR input, when high, synchronizes cascaded
V6118s by forcing a new time frame to begin at the next
falling edge of the FR input final (see Fig.6). A time frame
begins with row 1 and so the LCD picture is rebuilt from
row 1 each time cascaded V6118s are synchronized.
When cascading devices, all STR lines must be tied
together (see Fig. 10).
FR Input
The FR signal controls the segment output frequency
generation (see Fig. 7, 8 and 9). To avoid having DC on
the display, the FR signal must have a 50% duty cycle.
The frequency of the FR signal must be n times the
desired display refresh rate, where n is the V6118 version
no. (2, 4 or 8). For example, if the desired refresh rate is
40 Hz, the FR signal frequency must be 320 Hz for the
V6118 8. A selected row (on) is in phasewith the FR
signal (see Fig. 7, 8 and 9).
10
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