
6 LCD POWER SEQUENCING AND POWER SAVE MODES
C-2-24
EPSON
SID13705 PROGRAMMING NOTES
AND EXAMPLES
6.3 LCD Enable/Disable
The descriptions below cover manually powering the LCD panel up and down. Use the sequences
described in this section if the power supply connected to the panel requires more than 127 frames
to discharge on power-down, or if the panel requires starting the LCD logic well in advance of
enabling LCD power. Currently there are no known circumstances where the LCD logic must be
active well in advance of LCD power.
Note: If 127 frame period is to long, blank the display, then reprogram the Horizontal and Vertical
sizes to produce a shorter frame period before using these methods.
Power On/Enable Sequence
The following is a sequence for manually powering-up an LCD panel if LCD power had to be
applied later than LCD logic.
1. Set REG[03h] bit 3 (LCDPWR Override) to “1”. This ensures that LCD power will be held
disabled.
2. Enable LCD logic. This is done by either setting the GPIO0 pin low to disable hardware power
save mode and/or by setting REG[03h] bits 1-0 to "11" to disable software power save.
3. Count “x” Vertical Non-Display Periods (OPTIONAL).
“x” corresponds the length of time LCD logic must be enabled before LCD power-up, con-
verted to the equivalent vertical non-display periods. For example, at 72 HZ counting 36 non-
display periods results in a one half second delay.
4. Set REG[03h] bit 3 to “0” to enable LCD Power.
Power Off/Disable Sequence
The following is a sequence for manually powering-down an LCD panel. These steps would be
used if the power supply discharge requirements are larger than the default 127 frames.
1. Set REG[03h] bit 3 (LCDPWR Override) to “1” which will disable LCD Power.
2. Count “x” Vertical Non-Display Periods.
“x” corresponds to the power supply discharge time converted to the equivalent vertical non-
display periods. (see the previous example)
3. Disable the LCD logic by setting the software power save in REG[03h] or setting hardware
power save via GPIO0. Keep in mind that after setting the power save mode there will be 127
frames before the LCD logic signals are disabled.