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DAC53401: Schematic Review and Questions

Part Number: DAC53401

Hello there,

I had a few questions regarding the implementation of the DAC53401. Details below:

Aim: To use the DAC to generate a buffered DC voltage of 0.9V, which will be used for setting a bias in summing amplifiers


  1. Please review the circuit shown and let me know if it will operate with a 1.8V SoC for basic functionality. Is there anything I have missed?

  2. Do the I2C connections require pullups? If so, what value would you recommend?

  3. What is the feedback pin FB used for?

  4. I have connected the address pin A0 to a GPIO pin on the SoC, is this the correct way to communicate with it?

  5. I have sent a separate note for documentation feedback, but the DAC53401 datasheet does not show a clean schematic under the “Application” section. It only shows the DAC being connected to VDD and GND. I had to derive the capacitor connections from the layout diagram, and that diagram does not talk about I2C pull-ups etc. If possible, please update the datasheet.



  • Hi Ashwati,

    I'll answer your questions in a list below:

    1. Add I2C pullups. Connect FB pin to OUT.  The rest of the schematic looks good.
    2. Yes, the I2C pins do require pull-ups. A value of 5kΩ is sufficient. On our EVMs we use 10kΩ near the DAC53401, and 10kΩ near the I2C source for a total parallel resistance of 5k.
    3. The FB pin is the feedback path for the internal output buffer. The DAC53401 can be used as programmable comparator where the FB pin is the input to the comparator and the DAC output is the threshold. Also in the programmable LED biasing example given in the datasheet, the FB pin is connected to the source of the MOSFET to compensate the Vgs drop and corresponding drift of the MOSFET. If the FB pin is not used, connect it to the OUT pin to close the feedback path. 
    4. The A0 pin determines the lower 3 bits of the slave address of the device according to the table below. You can route this as a GPIO on the SoC, but it would be recommended to add a pull up or pull down to the pin as well. Alternatively, you can directly connect A0 to one of the 4 options (AGND, VDD, SDA, or SCL) based on the slave address you would like to use. 
    5. I will relay this comment to my team. In the mean time, you can take a look at the EVM schematic that is shown in the EVM users guide linked here

    Please let me know if there are any other questions.

  • Hello Katlynne,

    Thank you for the detailed response. I have edited the connections as you have suggested. Thank you for clarifying, and I will let you know if I have any other questions.