VGA (Video Graphics Array) offers high resolution, a high display rate, and a wide color range. The VGA connector is a standard interface on CRT displays and on LCD panels, and it is still widely used.
VGA OUT PCB Design Notes
- In the overall placement, put the VGA connector as close as possible to the conversion IC so the analog VGA traces stay short.
- Place every decoupling capacitor for the conversion-IC supplies next to the matching power pin.
- VGA_R/G/B each need a 75 Ω pulldown resistor with 1% tolerance. The resistors must sit next to the IC.
- Make the VGA_R/G/B traces as wide as practical, 12 mil or more recommended. Intra-group length mismatch must not exceed 200 mil.
- VGA_R/G/B must be ground-fenced for the full run. Place a ground via on the fence at least every 300 mil.
- The layer adjacent to VGA_R/G/B must be a ground plane, not a power plane.
- Keep VGA_R/G/B away from high-speed nets such as LCD and DRAM. Do not route them on the layer next to those high-speed nets. Do not change layer through vias next to high-speed nets. Do not route through an inductor area. Keep the traces away from RF signals and RF parts.
- Place the VGA_HSYNC/VSYNC RC filters next to the VGA connector. Those traces must not exceed 6 inches.
- Place TVS devices for every VGA-connector signal as close as possible to the connector. The topology is VGA connector → TVS → IC pin. When an ESD event occurs, the discharge must hit the TVS first. Do not leave a stub on the TVS traces. Add ground vias on the TVS ground pins; use at least two 0.4 × 0.2 mm vias to strengthen the ESD dump path.
