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TLC7226: DAC is not working when connected to more than 5 loads

Part Number: TLC7226

Hello Team,

We are using TLC7226 for one of our DAC application. We are using this DAC to control some loads which works on 0-10 volts analog voltage.

We are able to control 5 devices in one channel with each DAC, but when connected to more than 5 load devices DAC is not able to control those loads.

We are using STM32 controller and MC74HC4066A(buffer) analog switch for protection of DAC. When we removed the analog switch same issue happens.

Please help!

Thanks in advance.

  • Hi Srikanth,

    Can you share more details on the type of loads you are connecting (how much current are they drawing), and what you mean by:

    DAC is not able to control those loads

    What is the DAC behavior?

    Best,

    Katlynne Jones

  • Hi Katlynne,

    Thanks for response.

    We are trying to control some lighting drivers which will work on 0-10 volts. 

    When DAC gives 0 volts the lights will go to 0% intensity, when DAC gives 10 volts the lights will go to 100% intensity.

    DAC is able to handle 5 lighting drivers, when connected to 6th driver DAC not able to control the output voltage.

    How much is the sink current for each DAC?

    Thanks in advance.

  • Hi Srikanth,

    According to the datasheet each channel can source ~5mA of output current.

    Best,

    Katlynne Jones

  • Hi Katlynne,

    The loads we are connecting will give 1mA each to the DAC. DAC is able to handle 5 load devices after that the DAC voltage is nor reflected back to the load devices. Can we ant buffer or any other interface between DAC and loads such that DAC should able to control 12 or 15 load devices.

    Thanks in advance.

  • Hi Srikanth,

    Any output buffer that supports > 15mA of load current (1mA per load device in your system) should work for your design. If you are operating near the rails, look into a RR op amp that does not have significant load regulation drop for currents < 15mA especially at the rail.  

    Best,

    Katlynne Jones