Datasheet

 2009 Microchip Technology Inc. Preliminary DS41364D-page 335
PIC16F193X/LF193X
26.3 LCD Bias Voltage Generation
The LCD module can be configured for one of three
bias types:
• Static Bias (2 voltage levels: V
SS and VLCD)
• 1/2 Bias (3 voltage levels: VSS, 1/2 VLCD and
V
LCD)
• 1/3 Bias (4 voltage levels: VSS, 1/3 VLCD,
2/3 V
LCD and VLCD)
TABLE 26-2: LCD BIAS VOLTAGES
So that the user is not forced to place external compo-
nents and use up to three pins for bias voltage generation,
internal contrast control and an internal reference ladder
are provided internally to the PIC16F193X/LF193X. Both
of these features may be used in conjunction with the
external VLCD<3:1> pins, to provide maximum flexibility.
Refer to Figure 26-3.
FIGURE 26-3: LCD BIAS VOLTAGE GENERATION BLOCK DIAGRAM
Static Bias 1/2 Bias 1/3 Bias
LCD Bias 0 V
SS VSS VSS
LCD Bias 1 —1/2 VDD 1/3 VDD
LCD Bias 2 —1/2 VDD 2/3 VDD
LCD Bias 3 VLCD3VLCD3VLCD3
VDD
LCDIRE
x 3
3.072V
1.024V from
FVR
VLCD3
LCDIRS
LCDIRE
LCDIRS
LCDCST<2:0>
VLCD3PE
VLCD2
VLCD2PE
VLCD1
VLCD1PE
LCDRLP1
BIASMD
lcdbias3
lcdbias2
lcdbias1
lcdbias0
LCDA
LCDA
LCDA
LCDRLP0