• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 47 subscribers
  • Views 1260 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.

THS6012 PowerPad pad connections

Karne
Prodigy 210 points
Other Parts Discussed in Thread: THS6012, LMH6521

After soldering THS6012 and powering it up for first time it starts to heat immediately.  First suspect is pad - can it be connected to GND? Or left floating? I connected it to GND. Is that ok?

There nothing about it in datasheet but I seen somewhere on separate Powerpad app-note it should be grounded.  But may be for ths6012 is different....

  • 0
    TI__Genius 13935 points

    Hello Karne,

    I looked at the eval board datasheet for this part and it indicates that the thermal pad is electrically isolated from the die.  This means that it can be connected to ground, if desired. 


    Can you describe your board layout?    The THS6012 requires a fairly extensive amount of copper in the PCB to move heat away from the part.  A good way to do this is to flood the top and bottom side of your PCB with ground, and then use vias to move the heat from the internal ground plane to the outer ground metal. 

    If you look at the LMH6521 evaluation board this method was used to maximize heat dissipation. 

    http://www.ti.com/tool/lmh6521eval

  • 0 in reply to Loren Siebert 1
    Prodigy 210 points

    Hello Loren,

    Yes, I verified by disconnecting - that  is not a pad. However what - still mystery.  Each opamp takes 90mA. Load is totally removed (one 1ohm resistor taken out). I have 3 such circuits on pcb and all they are same, so can not bee all chips equally bad. Must be something in circuit design.

    Could you drop an eye to circuit above - anything suspicious? Since there is no load I assume it should be quiescent current only (~15mA) regardless of input.

  • 0 in reply to Karne
    TI__Genius 13935 points

    Hello Karne,

    I cannot read the component values in the attached schematic. 

    Try disconnecting the transformer, then measure the DC voltage that is applied to the transformer primary.  If there is a DC current in the trasformer primary that could be the problem.

    Also, what is the purpose of the capacitor between the two outputs?  Excessive capacitance can cause oscillation.