STE2002_06 ST Microelectronics, Inc., STE2002_06 Datasheet - Page 8

• Manufacturer Part Number: STE2002_06
• Description: 81 x 128 Single-chip LCD Controller/driver
• Manufacturer: ST Microelectronics, Inc.

Circuit description
2
2.1
2.2
2.3
2.4
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Circuit description
Supplies voltages and grounds
V
generator is not used, this should be connected to V
IC. V
Internal supply voltage generator
The IC has a fully integrated (no external capacitors required) charge pump for the Liquid
Crystal Display supply voltage generation. The multiplying factor can be programmed to be:
Auto, X6, X5, X4, X3, X2, using the ’set CP Multiplication’ Command. If Auto is set, the
multiplying factor is automatically selected to have the lowest current consumption in every
condition. This make possible to have an input voltage that changes over time and a
constant V
V
with temperature) can be programmed using the bits TC1 and TC0 and T2,T1 & T0. This will
ensure no contrast degradation over the LCD operating range. Using the internal charge
pump, the V
be connected to V
event the V
generator must be programmed to zero (PRS = [0;0], Vop = 0 - Reset condition).
Oscillator
A fully integrated oscillator (requires no external components) is present to provide the clock
for the Display System. When used the OSC pad must be connected to V
external oscillator could be used and fed into the OSC pin. An oscillator out is provided on
the OSCOUT Pad to cascade two or more drivers
Bias levels
To properly drive the LCD, six (Including VLCD and VSS) different voltage (Bias) levels are
generated. The ratios among these levels and VLCD, should be selected according to the
MUX ratio (m). They are established to be (Fig. 4):
DD2
LCDSENSE
DD1
is supply voltages to the internal voltage generator (see below). If the internal voltage
supply voltage could be different form V
V
LCD
LDCOUT
LCD
pad. For this voltage, eight different temperature coefficients (TC, rate of change
LCDIN
voltage. The output voltage (V
,
and V
n
------------ - V
n
LCDIN
and V
+
+
3
4
LCDOUT
to supply the LCD without using the internal generator. In such
LCDSENSE
LCD
,
pads must be connected together. An external supply could
n
------------ - V
n
+
+
must be connected to GND and the internal voltage
2
4
LCD
LCDOUT
,
------------ - V
n
DD2
2
+
4
DD1
.
) is tightly controlled through the
LCD
pad. V
,
------------ - V
n
DD1
1
+
4
supplies the rest of the
LCD
DD1
,V
SS
pad. An
STE2002