Microchip Technology DM183037 Data Sheet

Page of 696
 2012 Microchip Technology Inc.
DS30575A-page 245
PIC18F97J94 FAMILY
13.0 LIQUID CRYSTAL DISPLAY 
(LCD) CONTROLLER
The Liquid Crystal Display (LCD) driver module gener-
ates the timing control to drive a static or multiplexed
LCD panel. In 100-pin devices (PIC18F97J94), the
module drives panels of up to eight commons and up to
60 segments when 5 to 8 commons are used, and up
to 64 segments when 1 to 4 commons are used. It also
provides control of the LCD pixel data.
The LCD driver module supports:
• Direct driving of LCD panel
• Three LCD clock sources with selectable prescaler
• Up to eight commons:
- Static (One common)
- 1/2 multiplex (two commons)
- 1/3 multiplex (three commons)
- 1/8 multiplex (eight commons)
• Up to 60 segments (in 100-pin devices when 
1/5-1/8 multiplex is selected), 64 (in 100-pin 
devices when up to 1/4 multiplex is selected), 46 
(in 80-pin devices when 1/5-1/8 multiplex is 
selected), 50 (in 80-pin devices when up to 
1/4 multiplex is selected), 30 (in 64-pin devices 
when 1/5-1/8 multiplex is selected) and 34 (in 
64-pin devices when up to 1/4 multiplex is 
selected)
• Static, 1/2 or 1/3 LCD bias
• On-chip bias generator with dedicated charge 
pump to support a range of fixed and variable bias 
options
• Internal resistors for bias voltage generation
• Software contrast control for LCD using the 
internal biasing
A simplified block diagram of the module is shown in
FIGURE 13-1:
LCD CONTROLLER MODULE BLOCK DIAGRAM
COM<7:0>
Timing Control
Data Bus
SOSC
FRC Oscillator
LPRC Oscillator
512
to
64
MUX
SEG<63:0>
To I/O Pins
64 x 8
LCD DATA
LCDCONL
LCDPSL
LCDSEx
LCDDATA0
LCDDATA1
LCDDATA62
LCDDATA63
..
.
LCD Bias Generation
LCD Clock
Source Select
LCD
Charge Pump
64
8
Bias
Voltage
8
(Secondary Oscillator)
Resistor Ladder