SNLS650 May 2019 DS90UB949A-Q1
PRODUCTION DATA.
The HPD pin is asserted by the sink to let the source know that it is ready to receive the HDMI signal. The source initiates the connection by first providing the 5-V power signal through the HDMI interface. The sink holds HPD low until it is ready to receive signals from the source, at which point it will release HPD to be pulled up to 5 V.