• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 48 subscribers
  • Views 351 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

THS4561: Layout question

Joe Shell
Intellectual 1690 points
Part Number: THS4561
Other Parts Discussed in Thread: THS4551

Tool/software:

Can you please provide some guidance regarding the PCB Layout mentioned on page 36 of the THS4561’s data sheet.  I am using the WQFN 10 pin package (the diagram on page 36 only shows the layout for the VSSOP).  My question is that the data sheet recommends to cut out the power and ground planes underneath the components as shown on page 36.  However,  it also recommends that vias be placed close to the supply pins that are located in the cut out area where there is no plane to connect to.  I could run a trace, from beyond the cut out section, to the via but that seems counter intuitive to add that extra impedance.  The WQFN package seem to be more applicable for less cut out area due to the power pins being located at the two ends of the package.  Any advice on this would be appreciated.

  • 0
    TI__Expert 8650 points

    Hi Joe, 

    Cutting out the ground and power traces below the inputs helps reduce the total capacitance on the inputs caused by the PCB. This helps with stability, but it is more critical for very high speed devices. For a part like the THS4561, it should be fine without the cutouts in order to make the routing easier. We did something very similar with our THS4551 RUN package EVM which you can reference here: https://www.ti.com/lit/ug/slou451/slou451.pdf

    Best, 

    Jacob