PIC16F193X Datasheet, PDF (253/418 Pages) Microchip Technology – 28/40/44-Pin Flash-Based, 8-Bit CMOS Microcontrollers with LCD Driver and nanoWatt Technology

PIC16F193X/LF193X
21.4.3 AUTOMATIC POWER MODE
SWITCHING
As an LCD segment is electrically only a capacitor, cur-
rent is drawn only during the interval where the voltage
is switching. To minimize total device current, the LCD
internal reference ladder can be operated in a different
power mode for the transition portion of the duration.
This is controlled by the LCDRL Register
(Register 21-7).
The LCDLAD register allows switching between two
power modes, designated ‘A’ and ‘B’. ‘A’ Power mode
is active for a programmable time, beginning at the
time win the LCD segments transition. ‘B’ Power mode
is the remaining time before the segments or com-
mons change again. The LRLAT<2:0> bits select how
long, if any, that the ‘A’ Power mode is active. Refer
to Figure 21-4.
To implement this, the 5-bit prescaler used to divide
the 32 kHz clock down to the LCD controller’s 1 kHz
base rate is used to select the power mode.
FIGURE 21-4:
LCD INTERNAL REFERENCE LADDER POWER MODE SWITCHING DIAGRAM –
TYPE A
Single Segment Time
32kHz_clk
cnt[4:0]
lcd_clk
LRLAT[2:0]
Segment Data
Power Mode
‘H00 ‘H01 ‘H02 ‘H03 ‘H04 ‘H05 ‘H06 ‘H07
LRLAT<2:0>
Power Mode A
‘H3
Power Mode B
‘H0E ‘H0F ‘H00 ‘H01
Mode A
FIGURE 21-5:
LCD INTERNAL REFERENCE LADDER POWER MODE SWITCHING DIAGRAM –
TYPE B
Single Segment Time
32kHz_clk
cnt[4:0]
lcd_clk
LRLAT[2:0]
Segment Data
Power Mode
‘H00 ‘H01 ‘H02 ‘H03 ‘H04 ‘H05 ‘H06 ‘H07
LRLAT<2:0>
Power Mode A
‘H3
Power Mode B
‘H1E ‘H1F ‘H00 ‘H01
Mode A
© 2008 Microchip Technology Inc.
Preliminary
DS41364A-page 251