Microchip Technology IC PIC MCU PIC16F1937-I/PT TQFP-44 MCP PIC16F1937-I/PT Data Sheet

 2008-2011 Microchip Technology Inc.

DS41364E-page 337

27.4.3

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
(

The LCDRL register allows switching between two
power modes, designated ‘A’ and ‘B’. ‘A’ Power mode
is active for a programmable time, beginning at the
time when the LCD segments transition. ‘B’ Power
mode is the remaining time before the segments or
commons change again. The LRLAT<2:0> bits select
how long, if any, that the ‘A’ Power mode is active.
Refer to 

.

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.

Single Segment Time

‘H00

‘H01

‘H02

‘H03

‘H04

‘H05

‘H06

‘H07

‘H0E

‘H0F

‘H00

‘H01

‘H3

Power Mode A

Power Mode B

Mode A

LRLAT<2:0>

32 kHz Clock

Ladder Power

Segment Clock

LRLAT<2:0>

 Segment Data

Power Mode

COM0

SEG0

COM0-SEG0

Control

V

0

V

1

V

0

V

1

V

0

V

1

-V

1