STE2002DIE1 STMicroelectronics, STE2002DIE1 Datasheet - Page 6

• Manufacturer Part Number: STE2002DIE1
• Description: 81 x 128 Single Chip LCD Controller/Driver
• Manufacturer: STMicroelectronics

STE2002
CIRCUIT DESCRIPTION
Supplies Voltages and Grounds
V
not used, this should be connected to V
could be different form 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, us-
ing 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
the V
perature) 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
must be connected together. An external supply could be connected to V
using the internal generator. In such event the V
the internal voltage 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 Dis-
play System. When used the OSC pad must be connected to V
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):
Figure 4. Bias level Generator
thus providing an 1/(n+4) ratio, with n calculated from:
For m = 81, n = 6 and an 1/10 ratio is set.
For m = 65, n =5 and an 1/9 ratio is set.
6/51
DD2
LCDSENSE
is supply voltages to the internal voltage generator (see below). If the internal voltage generator is
pad. For this voltage, eight different temperature coefficients (TC, rate of change with tem-
V
L CD
DD2
.
n
------------ - V
n
+
+
3
4
LCD
LCD
voltage. The output voltage (V
,
DD1
n
------------ - V
n
nR
R
R
R
R
+
+
2
4
pad. V
n
=
LDCOUT
LCD
DD1
m 3
,
V
n + 3
n + 4
n + 2
n + 4
n + 4
n + 4
V
------------ - V
n
LCD
2
1
SS
–
2
+
supplies the rest of the IC. V
and V
·V
·V
·V
·V
D00IN1150
4
LCD
LCD
LCD
LCD
L CD
LCDSENSE
DD1
,
------------ - V
n
1
+
pad. An external oscillator could be
LCDOUT
4
LCDIN
must be connected to GND and
LCD
) is tightly controlled through
,V
to supply the LCD without
LCDIN
SS
DD1
and V
supply voltage
LCDOUT
pads