Lcd Power Sequencing And Power Save Modes; Introduction To Lcd Power Sequencing; Registers - Epson S1D13505F00A Technical Manual

6: LCD POWER SEQUENCING AND POWER SAVE MODES

6 LCD P
OWER

6.1 Introduction to LCD Power Sequencing

LCD Power Sequencing allows the LCD power supply to discharge prior to shutting down the LCD
signals. Power sequencing is required to prevent long term damage to the panel and to avoid
unsightly "lines" on power-down and power-up.
The S1D13505 performs automatic power sequencing when the LCD is enabled or disabled through
the LCD Enable bit in register [0Dh]. For most applications the internal power sequencing is the
appropriate choice.
There may be situations where the internal time delay is insufficient to discharge the LCD power
supply before the LCD signals are shut down. This section details the sequences to manually power-
up and power-down the LCD interface.
Proper LCD power sequencing dictates that there must be a time delay between the time the LCD
power is disabled and the time the LCD signals are shut down. During power up the LCD signals
must be active prior to applying power to the LCD. This time interval varies depending on the power
supply design. The power supply on the S5U13505P00C Evaluation board requires 0.5 seconds to
fully discharge. Your power supply design may vary.

6.2 Registers

REG[0D] Display Mode Register
Simultaneous Simultaneous
TM
SwivelView
Display Option Display Option
Enable
Select Bit 1 Select Bit 0
LCD Enable normally performs all the required power sequencing. Upon setting LCD Enable to '0'
the system will begin a series of events which include turning off the LCD power supply, waiting for
the power supply to discharge and finally turning off the LCD signals.
REG[1A] Power Save Configuration Register
Power Save
n/a
Status
LCD Power Disable would be used to manually sequence the events leading to an LCD power-
down. First the program would set LCD Power Disable to '1' to begin discharging the LCD power
supply. After waiting a pre-determined amount of time the software would Disable the LCD signals
using the LCD Enable bit in register [0Dh].
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S P
EQUENCING AND OWER
Bit-Per-Pixel Bit-Per-Pixel Bit-Per-Pixel
Select Bit 2 Select Bit 1 Select Bit 0
Suspend
LCD Power
n/a n/a Refresh Select
Disable
Bit 1
EPSON
S M
AVE ODES
CRT Enable LCD Enable
Suspend Software Sus-
Refresh Select pend Mode
Bit 0 Enable
S1D13505 PROGRAMMING NOTES
AND EXAMPLES (X23A-G-003-05)