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ADI Part || ADV7391 || Power Consumption

Hi,
We are using the ADV7391, 10-Bit Video Encoder, NTSC/PAL, LFCSP-32 in our ongoing project and it is working fine.
 
Now we were optimizing the power of the board and below are the observations:
 
1. When  RSET = 510 Ω, RL = 37.5 Ω (Full Drive Mode), the board is working and we can see the video output on TV and current consumption is 39mA.
2. When  RSET = 4.12 kΩ, RL = 300 Ω ( Low-Drive Output Current ),  current consumption is 5mA but no output is visible on TV.
Please suggest how we can run the ADV7391 in Low Drive mode to reduce the current and see the output on the TV.
  • Hi,

      As per specification, low drive mode typical current value is 4.3 mA when (RSET=4.12 kΩ,RL=300 Ω) -  For low drive operation, RSET must have a value of 4.12 kΩ, and RL must have a value of 300 Ω. The resistor connected to the RSET pin should have a 1% tolerance.

     Please note the encoders expect to be terminated with 75 ohms on your PCB with another 75 ohms at the end of the transmission line, so the total load resistance is 37.5 Ohms ( load consists of a 75 Ohm resistor to ground right next to the pin and a 75 Ohm resistor to ground at the sink.  Normal cables plus sinks are set up this way ).

    Thanks,

    Poornima