Page 38
Epson Research and Development
Vancouver Design Center
7 LCD Power Sequencing
The S1D13506 is designed with internal circuitry which automates LCD power sequencing
(the process of powering-on and powering-off the LCD panel). LCD power sequencing
allows the LCD bias voltage to discharge prior to shutting down the LCD signals,
preventing long term damage to the panel and avoiding unsightly “lines” at power-
on/power-off.
Proper LCD power sequencing for power-off requires a delay from the time the LCD power
is disabled to the time the LCD signals are shut down. Power-on requires the LCD signals
to be active prior to applying power to the LCD. This time interval varies depending on the
LCD bias power supply design. For example, the LCD bias power supply on the S5U13506
Evaluation board requires 0.5 seconds to fully discharge. Other power supply designs may
vary.
For most applications automatic power sequencing is the appropriate choice, see Section
7.1, “Automatic Sequencing” . However, there may be situations where the internal time
delay is insufficient to discharge the LCD bias power supply before the LCD signals are
shut down. For the sequence used to manually power-off the LCD panel, see Section 7.2,
“Manual Sequencing” .
7.1 Automatic Sequencing
LCD power sequencing is automatically provided when the S1D13506 is powered-on or
powered-off using the built-in Power Save Mode. The Power Save Mode is enabled using
REG[1F0h] bit 0. For more information on Power Save Mode, see Section 6, “Power Save
Mode” .
For LCD power sequencing AC Timing, see the S1D13506 Hardware Functional
Specification, document number X25B-A-001-xx.
7.2 Manual Sequencing
In cases where automatic LCD power sequencing is not applicable, manual sequencing can
be done. This section assumes the LCD bias power is controlled through GPIO1. The
S1D13506 GPIO pins are multi-use pins and may not be available in all system designs.
For further information on the availability of GPIO pins, see the S1D13506 Hardware
Functional Specification, document number X25B-B-001-xx.
S1D13506
X25B-G-003-03
Programming Notes and Examples
Issue Date: 01/02/06
EPSON [ EPSON COMPANY ]
