The Apple Display Connector (ADC) carries both digital and analog video signals. It also carries USB and control signals along with power for an external monitor such as the 17-inch Apple Studio Display, the 15-inch plat-panel Apple Studio Display, or the 22-inch Apple Cinema Display.
Figure 3-3 shows the contact configuration; Table 3-6 and Table 3-7 list the signals and pin assignments.
Figure 3-3 Apple Display Connector
C1 | Analog Blue Video |
C2 | Analog Green Video |
C3 | Analog Horizontal Sync |
C4 | Analog Red Video |
C5 | Analog RGB Return and DDC Return |
The maximum current available from the 28-V supply for the external monitor is 4.0 A.
The Soft Power signal puts the monitor into a low-power mode when the computer is in Sleep mode.
The graphics data sent to the digital monitor use transition minimized differential signaling (TMDS). TMDS uses an encoding algorithm to convert bytes of graphics data into characters that are transition-minimized to reduce EMI with copper cables and DC-balanced for transmission over fiber optic cables. The TMDS algorithm also provides robust clock recovery for greater skew tolerance with longer cables or low cost short cables. For additional information about TMDS, see the references in Digital Visual Interface.