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Please tell me about Video DAC (ADV7125) current limit.

Category: Datasheet/Specs
Product Number: ADV7125
Software Version: non

I believe that the current control of the RGB analog signal output can be controlled using the RSET pin.
Is it possible to make it smaller than 530Ω under the following conditions?
If it is possible to make it smaller, could you please tell me how small it can be made? (I want to increase the current flowing.)

-conditions-
SYNC pin=low, VAA=3.3V

(Intent of question)
The value of RSET can be calculated using the following formula
I interpret it as IOR, IOB,IOG (mA) = 7989.6 × VREF (V)/RSET (Ω)

FEATURES has the following information
It says DAC output current range:2.0mA to 26.5mA, is max26.5mA the limit?

The value listed in FEATURES is range:2.0mA to 26.5mA, so
According to this description, if the SYNC pin is set to High, up to 26.5mA can be used.

When SYNC pin is set to low, it can be used up to 18.5mA ←When SYNC pin is set to low, 18.5mA is the limit value?
In the circuit example in the data sheet, the resistance value of RSET is 530Ω.
7989.6 × VREF (V)/RSET (Ω)=7989.6 x 1.235 / 530 =18.61mA ←Exceeds 18.5mA

I think my interpretation is fundamentally wrong, so I'd like to confirm.
Increase the current (analog signal voltage value Vp-p) as much as possible.
The purpose is to strengthen noise resistance.

Parents
  • Hi,

    Please note " DAC output current is proportional to Rset and Rload. DAC is a current output based on digital input values, Rset and Rload.
    If you increase Rload by 20% the effective output voltage would increase by 20% with the caveat that the output voltage does not exceed limit.
    We do not test this or specify these limits beyond what is defined in the data sheet.

    When Rset = 510 Ohms, the DAC outputs expect to see a 37.5 Ohm load. The 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.

    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.

    A resistor connected between the RSET pin and AGND is used to control the full-scale output current and, therefore, the output voltage levels of DAC .

     Note : The output current is based on the equations given in the data sheet

    The Max output current are defined in the Reference Input equations with the caveat you do not exceed the absolute voltages and values.

    Thanks,

    Dharani S

Reply
  • Hi,

    Please note " DAC output current is proportional to Rset and Rload. DAC is a current output based on digital input values, Rset and Rload.
    If you increase Rload by 20% the effective output voltage would increase by 20% with the caveat that the output voltage does not exceed limit.
    We do not test this or specify these limits beyond what is defined in the data sheet.

    When Rset = 510 Ohms, the DAC outputs expect to see a 37.5 Ohm load. The 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.

    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.

    A resistor connected between the RSET pin and AGND is used to control the full-scale output current and, therefore, the output voltage levels of DAC .

     Note : The output current is based on the equations given in the data sheet

    The Max output current are defined in the Reference Input equations with the caveat you do not exceed the absolute voltages and values.

    Thanks,

    Dharani S

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