What is DVI?
DVI (Digital Video Interface) is a video connector designed by an industry consortium, the Digital Display Working Group (DDWG), to maximize the visual quality of digital display devices (i.e. LCD, Flat panel, etc…).
Technical Overview
Digital video transmission transmits the brightness of the pixels as a series of binary numbers. When the video display (running at its native resolution) receives this information, it displays each individual pixel at its corresponding brightness. Examples of digital display devices include flat panel, LCD, and digital projectors.
Analog transmission occurs when the source transmits each line of horizontal image at a time, and varies the output voltage to correspond to changing brightness. Examples of analog display devices include CRT based devices. VGA is an example of analog display standard.
Digital video devices and transmission produces a more accurate and vivid image than analog, because display information for each individual pixel is transmitted individually.
Dual link DVI transmits double the informational capacity of single link, allowing extremely high resolution displays (> 2.3 million pixels). Apple Computer’s 30-inch Cinema HD Display was a dual link DVI trailblazer, with a 2560 x 1600 max resolution (>> 4 million pixels).
Connector Types
There exists three main types of DVI connectors:
- DVI-D (digital only)
- DVI-A (analog only)
- DVI-I (integrated digital and analog)
DVI-D is compatible with a connection between a digital source and a digital display device. Many new DVD players, computer video cards, TV sets (i.e. HDTV), and projectors support this type of connection. DVI-D comes in both single link and dual link. The below pin diagram shows the a DVI-D single link and a dual link connector.
DVI-A is compatible with a connection between an analog source and a analog display device. Even new digital sources usually have backward compatibility with analog display devices (i.e. CRT monitor). DVI-A comes in single link form only. The below pin diagram shows a DVI-A connector.
| DVI-A |
 |
| DVI-A Cables (Male to Female) DVI-A Cables (Male to Male) DVI-A to VGA Cables (Male to Male) DVI-A Male to VGA Female Adapter |
DVI-I has both digital and analog compatibility; and therefore, is dynamically versatile, having the capability to interchange between digital and analog components without additional hardware. DVI-I come in both single link and dual link variants (for the digital capability). The below pin diagram shows a DVI-I single link and a dual link connector.
Specifications
Digital
- Minimum clock frequency: 21.76 MHz
- Maximum clock frequency in single link mode: Capped at 165 MHz
- Maximum clock frequency in dual link mode: Limited only by cable
- Pixels per clock cycle: 1 (single link) or 2 (dual link)
- Bits per pixel: 24
- Example display modes (single link):
- HDTV (1920 × 1080) @ 60 Hz with 5% LCD blanking (131 MHz)
- UXGA (1600 × 1200) @ 60 Hz with GTF blanking (161 MHz)
- SXGA (1280 × 1024) @ 85 Hz with GTF blanking (159 MHz)
- Example display modes (dual link):
- QXGA (2048 × 1536) @ 75 Hz with GTF blanking (2×170 MHz)
- HDTV (1920 × 1080) @ 85 Hz with GTF blanking (2×126 MHz)
- 2560 × 1600 pixels (on 30″ LCD)
Analog
- RGB bandwidth: 400 MHz at -3dB
Connector
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | C1 | C2 | |
| 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | C5 | ||
| 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | C3 | C4 | |
| Pin | Name | Function |
| 1 | TMDS Data 2- | Digital red – (Link 1) |
| 2 | TMDS Data 2+ | Digital red + (Link 1) |
| 3 | TMDS Data 2/4 shield | |
| 4 | TMDS Data 4- | Digital green – (Link 2) |
| 5 | TMDS Data 4+ | Digital green + (Link 2) |
| 6 | DDC clock | |
| 7 | DDC data | |
| 8 | Analog Vertical Sync | |
| 9 | TMDS Data 1- | Digital green – (Link 1) |
| 10 | TMDS Data 1+ | Digital green + (Link 1) |
| 11 | TMDS Data 1/3 shield | |
| 12 | TMDS Data 3- | Digital blue – (Link 2) |
| 13 | TMDS Data 3+ | Digital blue + (Link 2) |
| 14 | +5V | Power for monitor when in standby |
| 15 | Ground | Return for pin 14 and analog sync |
| 16 | Hot Plug Detect | |
| 17 | TMDS data 0- | Digital blue – (Link 1) and digital sync |
| 18 | TMDS data 0+ | Digital blue + (Link 1) and digital sync |
| 19 | TMDS data 0/5 shield | |
| 20 | TMDS data 5- | Digital red – (Link 2) |
| 21 | TMDS data 5+ | Digital red + (Link 2) |
| 22 | TMDS clock shield | |
| 23 | TMDS clock+ | Digital clock + (Links 1 and 2) |
| 24 | TMDS clock- | Digital clock – (Links 1 and 2) |
| C1 | Analog Red | |
| C2 | Analog Green | |
| C3 | Analog Blue | |
| C4 | Analog Horizontal Sync | |
| C5 | Analog Ground | Return for R, G and B signals |
For more information, see: http://en.wikipedia.org/wiki/DVI