SNLS477B October 2014 – November 2018 DS90UB948-Q1
The "UH" Deserializers support AV MUTE functionality when receiving the specifically defined data pattern (0x666666) during the blanking period (DE = LOW). Once the device enters the AV MUTE state, the device mutes both audio and video outputs resulting in a black display screen.
Be advised if the video source continues sending random data during blanking interval, the DS90UB948-Q1 may inadvertently enter the AV MUTE state upon receiving random data matching the AV MUTE command pattern. When paired with a UB version FPD-Link compatible serializer, setting the gate DE Register 0x04 will prevent video signals from being sent during the blanking interval. This will ensure AV MUTE mode is not entered during normal operation. By default the Data Enable (DE) signal is assumed to be active high. If DE is active low, then setting DE_POLARITY register bit 0x12 bit = 1 is also required. With the DE permanently LOW, deserializers do not check for the AV Mute conditions, so the AV Mute is not an issue when operating with HSYNC/VSYNC only mode displays.
If unexpected AV MUTE state is seen, it is recommended to verify checking the data path control setting of the paired Serializer. This setting is not accessible from DS90UB948Q-Q1.