DP_PWR Pin[edit]
Pin 20 on the DisplayPort connector, called DP_PWR, provides 3.3 V (±10%) DC power at up to 500 mA (minimum power delivery of 1.5 W).
[9](§3.2) This power is available from all DisplayPort receptacles, on both source and display devices. DP_PWR is intended to provide power for adapters, amplified cables, and similar devices, so that a separate power cable is not necessary.
Standard DisplayPort cable connections do not use the DP_PWR pin. Connecting the DP_PWR pins of two devices directly together through a cable can create a
short circuit which can potentially damage devices, since the DP_PWR pins on two devices are unlikely to have exactly the same voltage (especially with a ±10% tolerance).
[39] For this reason, the DisplayPort 1.1 and later standards specify that passive DisplayPort-to-DisplayPort cables must leave pin 20 unconnected.
[9](§3.2.2)
However, in 2013 VESA announced that after investigating reports of malfunctioning DisplayPort devices, it had discovered that a large number of non-certified vendors were manufacturing their DisplayPort cables with the DP_PWR pin connected:
Recently VESA has experienced quite a few complaints regarding troublesome DisplayPort operation that ended up being caused by improperly made DisplayPort cables. These "bad" DisplayPort cables are generally limited to non-DisplayPort certified cables, or off-brand cables. To further investigate this trend in the DisplayPort cable market, VESA purchased a number of non-certified, off-brand cables and found that an alarmingly high number of these were configured improperly and would likely not support all system configurations. None of these cables would have passed the DisplayPort certification test, moreover some of these cables could potentially damage a PC, laptop, or monitor.
The stipulation that the DP_PWR wire be omitted from standard DisplayPort cables was not present in the DisplayPort 1.0 standard. However, DisplayPort products (and cables) did not begin to appear on the market until 2008, long after version 1.0 had been replaced by version 1.1. The DisplayPort 1.0 standard was never implemented in commercial products.
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