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TPS92075 supply current

Oleksiy Pazyuk
Expert 2585 points

To estimate additional power consumption and degradation of the efficiency of the system when is used linear power supply to biasTPS92075 it will be useful to have values of the current supply of the IC.

In the datasheet is mentioned  quiescent current under non switching condition - Iccmax=2.5mA. 

As I understand in switch mode the current consumption of the driver itself will increase. Is there any data about  supply current for different switching frequencies?

  • 0
    TI__Intellectual 1115 points

    Hello, you are right, you need to consider the requirement of switching the FET and the frequency you are operating at.  For everything you ever wanted to know about it, refer to this very nice article by Laszlo Balogh: http://www.ti.com/lit/ml/slup169/slup169.pdf   From his article we are reminded that:

    Pgate=Vdrv*Qg*f_drv   OR I_to_drive_gate= Qg*f_drv.

    For a good estimate of the linear requirement you can add I_to_drive_gate to the current requirement of the linear.

    Say the FET gate charge was 4.5nC and you were running at 100kHz and the 12V linear was from 120V: (120-12)*4.5nC*100kHz=48.6mW in the linear. That would translate to ~5 degree increase in FET temperature for your average D-Pak due to the gate drive requirements only.

  • 0 in reply to Tim Sullivan
    Expert 2585 points

    Thanks Tim for the reply.

    I understand your statement of the additional current to supply  equal to the I_to_drive_gate= Qg*f_drv.

    As well thanks for your remark about power dissipation  due to frequency and gate charge of the external FET. But I guess you talk about SOIC package of the TPS92075D with Junction-to-ambient thermal resistance 112.3C/W. Because in other case I'm not sure what you mean under D-Pak.

     

  • 0 in reply to Oleksiy Pazyuk
    TI__Intellectual 1115 points

    ...right, ok.. When your original post mentioned the requirements of the linear I assumed you were worried about that device - the FET used in the linear regulator. This is often examined carefully as customers wish to shrink this device as much as possible. The temperature increase in the controller itself is very small.