An Overview of Current Display Interfaces

5
DVI
The Digital Visual Interface, or DVI, standard was published by the Digital Display
Working Group (DDWG) in 1999. The DDWG was an ad-hoc consortium of seven
PC-industry companies – HP, Compaq, Intel, IBM, NEC, Fujitsu, and Silicon Image
(the developer of the Transition Minimized Differential Signaling or TMDS electrical
interface on which the standard was based). DVI became the first reasonably-
successful digital display interface for PC monitors. However, the DDWG group has
not met for over five years, and may be considered defunct. Further development of
the DVI specification is not expected.
DVI is available in two forms: DVI-I, which includes both a VGA-compatible set of
analog video signals and a digital interface, and DVI-D, which is digital-only. The
digital interface may provide either one or two links, depending on the data
capacity needed. In DVI parlance, a single link consists of three differential data
pairs and a clock pair, and provides 4.8 Gbits/second of raw data capacity. Dual-
link versions of either DVI add three additional data pairs, for 9.6 Gbits/sec. total
capacity. DVI-I and DVI-D may be distinguished by the four-pin Microcross™ section
which carries the analog video signals; it is not present in DVI-D implementations.
DVI was at one time the most popular digital interface for monitors, but now its
share is rapidly declining in favor of the DisplayPort interface for PC applications.
DVI has already been virtually replaced in the CE/ TV market by HDMI.
Figure 2. DVI Connector
Table 2. DVI Connector Pinout
Pin
Signal
Pin
Signal
Pin
Signal (DVI-I only)
1
TMDS Data 2-
13
TMDS Data 3+
C1
Red analog video
2
TMDS Data 2+
14
+5 VDC
C2
Green video analog
3
TMDS Data shield
15
Ground/return
C3
Blue analog video
4
TMDS Data 4-
16
Hot plug detect
C4
Horizontal sync
5
TMDS Data 4+
17
TMDS Data 0
C5
Common return
6
DDC clock
18
TMDS Data 0
7
DDC data
19
TMDS Data shield
8
Vert. sync (DVI_I)
20
TMDS Data 5-
9
TMDS Data 1-
21
TMDS Data 5+
10
TMDS Data 1+
22
TMDS Data shield
11
TMDS Data shield
23
TMDS Clock +
12
TMDS Data 3-
24
TMDS Clock -
DVI-D
DVI-I
NOTE;
TMDS data pairs 3, 4, and 5
are present or active only in
“dual-link” implementations.