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TIDA-00559: Function of D6,D7 on this design

Nam, Dino
Expert 6445 points
Part Number: TIDA-00559
Other Parts Discussed in Thread: DAC8760

Dear team, 

I found TI reference design for DAC8760 combined output. 

There are questions on this design.

1. Is there a special reason why it was designed in the second stage? 

2. DESD1P0RFWQ-7 is obsolete part, can you recommend TI TVS device to replace this part? 

Thank you. 

  • +1
    TI__Prodigy 610 points

    Dear Dino,
    please see my comments to your questions as follows:


    1. the 2 stage current steering approach was used to reduce especially the forward current through D6 during surge conditions to ensure a lowest possible forward voltage drop on D6. This low forward voltage drop divided by R12 gives finally the current flow through U3's internal protection circuit which needs to be smaller than 10mA.
    This could for sure be achieved by using larger resistor values for R12, R13 and R14 - but this would result also in larger undesired voltage drops when operated as current output.

    2. According to what I have seen, DESD1P0RFWA can be considered as a replacement.

    Best Regards
    Juergen