PIC16F1946 Datasheet, PDF (337/440 Pages) Microchip Technology – 64-Pin Flash-Based, 8-Bit CMOS Microcontrollers with LCD Driver and nanoWatt XLP Technology

PIC16F/LF1946/47
26.3 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 26-2: 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 PIC16F/LF1946/47. Both of
these features may be used in conjunction with the exter-
nal VLCD<3:1> pins, to provide maximum flexibility. Refer
to Figure 26-3.
FIGURE 26-3:
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
 2010 Microchip Technology Inc.
Preliminary
DS41414A-page 335