SPC8104 S-MOS Systems, SPC8104 Datasheet - Page 286

• Manufacturer Part Number: SPC8104
• Description: VGA LCD CONTROLLER
• Manufacturer: S-MOS Systems

1.4
Depending on the specific LCD panel, it may require a positive power supply to provide between
+23V and +40V (Iout=45 mA) for use as the LCD BIAS voltage. For ease of implementation, such
a power supply has been provided as an integral part of this design The VDDH signal can be
found on LCD connector J5 at pin 34. Output voltage is varied by potentiometer R?. To prevent
panel damage, VDDH power supply sequencing is implemented by enabling the VDDH power
supply only when the SPC8104F0A signal LCDPWR# is at a low logic level.
1.5
Depending on the specific LCD panel, it may require a negative power supply to provide between
-18V and -23V (Iout=45 mA) for use as its LCD BIAS voltage. For ease of implementation, such a
power supply has been provided as an integral part of this design. The VLCD signal can be found
on LCD connector J5 at pin 32. Output voltage is varied by potentiometer R?. To prevent panel
damage, VLCD power supply sequencing is implemented by enabling the VLCD power supply
only when the SPC8104F0A signal LCDPWR# is at a low logic level.
External Oscillator Support
A 3.3V, 24.0MHz oscillator is provided on-board.
Fixed 3.3V Power Supply
There is a fixed 3.3V power supply on-board used by the SPC8104, DRAM and all associated
voltage translator circuitry.
Voltage Translation Circuitry for ISA-Bus Interface
Voltage translation circuitry is required on all ISA-Bus interface signals to prevent the forward
biasing of the input protection diodes of the SPC8104F0A bi-directional control of the data bus is
controlled by the output signal RDACK#. The LCD interface also has translation circuits as most
panels require a 5.0V interface.
PCB Layout Considerations
This will be a 4 layer PCB with its physical dimensions defined by ISA-Bus and component size
restrictions. All appropriate components will be surface-mount in an effort to reduce layout size.
All end-user controls (i.e., adjustable potentiometers, Dip-Switches, LCD Connector, etc.) will be
located on the top edge on the PCB allowing for ease of use.
Schematic Notes
The evaluation boards may have been modified and therefore the following schematics may not
reflect the actual implementation. Please request updated information before starting any hard-
ware design.
SDU8104B
EV2-10
Adjustable LCD BIAS Positive Power Supply
Adjustable LCD BIAS Negative Power Supply
S-MOS Systems, Inc. • Tel: [phone] • Fax: [phone] • http://www.smos.com
0C
Rev 1.1 ISA Bus Evaluation Board
412-1.0
SPC8104