Lcd Power Sequencing And Power Save Modes; Introduction To Lcd Power Sequencing; Introduction To Power Save Modes; Registers - Epson S1D13504 Technical Manual

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5 LCD Power Sequencing and Power Save Modes

5.1 Introduction to LCD Power Sequencing

5.2 Introduction to Power Save Modes

5.3 Registers

Display Mode Register
REG[0D]
Simultaneous
Display
n/a
Option Select
Bit 1
Power Save Configuration Register
REG[1A]
n/a n/a
S1D13504
X19A-G-002-07
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 start-up.
LCD Power Sequencing is performed on the S1D13504 through a software procedure even when
using hardware power save modes. Most "green" systems today use some sort of software power
down procedure in conjunction with external circuitry to set hardware suspend modes. These proce-
dures typically save/restore state information, or provide a timer prior to initiating power down. The
S1D13504 requires a timer between the time the LCD power is disabled and the time the LCD
signals are shut down. Conversely, the LCD signals must be active prior to the power supply starting
up. For simplicity, we have chosen to use the same time value for power up and power down proce-
dures.
The time interval required varies depending on the power supply design. The power supply on the
S5U13504B00C Evaluation board requires 0.5 seconds to fully discharge. Your power supply
design may vary.
Below are the procedures for all cases in which power sequencing is required.
The S1D13504 has two power save modes. One is hardware-initiated via the SUSPEND# pin, the
other is software-initiated through REG[1A] bit 0. Both require power sequencing as described
above.
Register bits discussed in this section are highlighted.
Simultaneous
Number of
Display
BPP Select
Option Select
Bit 2
Bit 0
n/a n/a
Suspend Refresh Select bits [1:0] should be set on power up depending on the type of DRAM
available. See the Hardware Functional Specification, document number X19A-A-002-xx.
Number of Number of
BPP Select BPP Select
Bit 1 Bit 0
Suspend
LCD Power
Refresh
Disable
Select Bit 1
Epson Research and Development
Vancouver Design Center
CRT Enable LCD Enable
Suspend Software
Refresh Suspend
Select Bit 0 Mode Enable
Programming Notes and Examples
Issue Date: 01/02/01