Adjustable Lcd Panel Positive Power Supply; Crystal Support; Cpu/Bus Interface Header Strips; Schematic Notes - Epson SED1352 Technical Manual

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1.3.7 Adjustable LCD Panel Positive Power Supply

Most single Monochrome 640x480 STN LCD panels require a positive power supply to provide between +23V and +40V
(I =45mA). For ease of implementation, such a power supply has been provided as an integral part of this design. The
out
signal VDDH can be adjusted by R8 (100K potentiometer) to provide an output voltage from +23 V to +40 V and is
enabled/disabled by the control signal LCDENB.
Note
LCDENB is directly controlled by register AUX[01], bit 4, of the SED1352. The VDDH power supply used on the
SDU1352 requires a logic "1" to disable it. As the signal LCDENB is a logic "0" at power-up, it is inverted by ex-
ternal logic to disable VLCD and prevent damaging the panel connected to the SDU1352.
Determine the panel's specific power requirements and set the potentiometer accordingly before connecting the panel.

1.3.8 Crystal Support

The input crystal frequency may be up to 25.175MHz depending on the specific panel size and frame rate desired.
Refer to Section 9.3 of the SED1352 Functional Specification, Drawing Office No. X16-SP-001-xx for further details.

1.3.9 CPU/Bus Interface Header Strips

All of the CPU/Bus interface pins of SED1352 are connected to the header strips H1 and H2 for easy interface to a
CPU/Bus other than the ISA bus.
Refer to Table 1-5, "CPU/BUS Connector H1 Pinout," on page 10 and Table 1-6, "CPU/BUS Connector H2 Pinout," on
page 11 for specific settings.
Note
These headers only provide the CPU/Bus interface signals from SED1352, when MC68K interface is selected (SW1-3
closed), external decoding logic MUST be used to access the SED1352.

1.3.10 Schematic Notes

The evaluation boards may have been modified and therefore the following schematics may not reflect the actual imple-
mentation. Please request updated information before starting any hardware design.
SED1352
X16-AN-002-09
Epson Research and Development
SDU1352B0C Rev. 1.0 Evaluation Board User Manual
Vancouver Design Center
Issue Date: 98/10/07