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DAC7564: UV LED controlling using DAC

Sebastian P J
Expert 1775 points
Part Number: DAC7564

Hi,

As a part of my new project I need to redesign UV LED driving circuit. Here I am using TI’s AM335x processor and using the SPI I have connected one DAC – LTC2668-12. The DAC output is going to the UV LED - NSHU591C. The specification of UV LED is given below.

(Highlighted one is using).

The DAC output (set to 0.068V) is connected to OpAmp (OPA4140) circuit and it is used for constant current sourcing (correct me if my understanding is wrong). The circuit is given below.

The UV LED’s cathode is connected to the non-inverting terminal of the amplifier B for current measuring.

DAC_VOUT1 – DAC channel 1 output.

LED1_A – UV LED Anode

LED1_K – UV LED Cathode

I have some queries on this.

  1. Currently in the circuit a 12-bit 16channel DAC is using, I have a plan to replace the DAC with TI’s DAC7564. Will it compatible with the above OpAmp circuit or suggest some other DAC having 4 channel and better accuracy.
  2. Is there any other method to drive the UV LED with constant current. 

Thanks

Sebastian

  • 0
    TI__Mastermind 18546 points

    Hi,

    You can replace LT2668 with DAC7564 without any issues. Whats the current you need for the UV LED's? I didn't see this information from the post.

    Also you don't need to have this complex circuit to achieve constant current with DAC and Op amp.

    In your circuit, how are you controlling the current? Please see below link for how to use DAC and op amp to create a constant current circuit.

    https://www.ti.com/lit/pdf/slaa884

     

    Regards,

    AK