PIC16F1938_13 Datasheet, PDF (333/488 Pages) Microchip Technology – 28/40/44-Pin Flash-Based, 8-Bit CMOS Microcontrollers with LCD Driver

PIC16(L)F1938/9
27.4 LCD Bias Voltage Generation
The LCD module can be configured for one of three
bias types:
• Static Bias (2 voltage levels: VSS and VLCD)
• 1/2 Bias (3 voltage levels: VSS, 1/2 VLCD and
VLCD)
• 1/3 Bias (4 voltage levels: VSS, 1/3 VLCD,
2/3 VLCD and VLCD)
TABLE 27-2: LCD BIAS VOLTAGES
Static Bias 1/2 Bias
1/3 Bias
LCD Bias 0
LCD Bias 1
LCD Bias 2
LCD Bias 3
VSS
—
—
VLCD3
VSS
1/2 VDD
1/2 VDD
VLCD3
VSS
1/3 VDD
2/3 VDD
VLCD3
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 PIC16(L)F193X. Both of
these features may be used in conjunction with the exter-
nal VLCD<3:1> pins, to provide maximum flexibility. Refer
to Figure 27-3.
FIGURE 27-3:
LCD BIAS VOLTAGE GENERATION BLOCK DIAGRAM
VDD
1.024V from
FVR
x3
3.072V
LCDIRE
LCDIRS
LCDA
LCDIRE
LCDIRS
LCDA
LCDRLP1
LCDRLP0
VLCD3
VLCD3PE
LCDCST<2:0>
LCDA
lcdbias3
VLCD2
VLCD2PE
VLCD1
VLCD1PE
lcdbias2
BIASMD
lcdbias1
lcdbias0
 2011-2013 Microchip Technology Inc.
DS40001574C-page 333