VGAX49

Features

• Digital VGA adapter
• 16-bit digital video
  • 5:6:5 (R:G:B) mapping (maximum)
  • 2:2:2 (R:G:B) mapping (option)
• Uses summing resistors
• DB-15F connector
• 49x49mm ODAS form factor
• Mounting holes

Connectors

Simulation

2:2:2 Resistor Simulation

• 3.3V Drive out of FPGA
• 1V is drive level for VGA specification
• 8 mA max drive current
• VGA presents a 75 Ohm load
• Series resistors present a voltage divider between the resistors on the card and the VGA load
• 1V at 75 Ohms is 13.3 mA
• Each color is independently driven
• The resistor with the smallest resistance value has larger current from the FPGA pin
• Current switches from source to sink depending on the voltages on the other resistors
• Use common value, 1% resistors
• 330 Ohm series resistor into a 75 Ohm load is 8.15 mA
  • Voltage with 330/75 ohm voltage divider is 0.61V - not full brightness

5:6:5 Resistor Simulation

• 3.3V Drive out of FPGA
• 1V is drive level for VGA specification
• 8 mA max drive current
• VGA presents a 75 Ohm load
• Series resistors present a voltage divider between the resistors on the card and the VGA load
• 1V at 75 Ohms is 13.3 mA
• Each color is independently driven
• The resistor with the smallest resistance value has larger current from the FPGA pin
• Current switches from source to sink depending on the voltages on the other resistors
• Use common value, 1% resistors
• 330 Ohm series resistor into a 75 Ohm load is 8.15 mA
  • Voltage with 330/75 ohm voltage divider is 0.61V - not full brightness

Schematic

• VGAX49 schematic

Assembly Sheet

• VGAX49 Assembly Sheet