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UCC28881: blanking time

Pol REYMOND
Intellectual 2030 points
Part Number: UCC28881

Hi team,

My customer is using the UCC28881 to make a Fly-buck.

Here are the characteristics of this Fly-buck:

• Single-phase variable input voltage 85V rms - 265V rms

• Non isolated output (VOUT) 10V 10mA

• Isolated output (VAUX) 5V 300mA

The characteristics of the coupled inductors used for this Fly-buck cause a spike on the primary current at each closing of the internal MOSFET of the UCC28881. 

The Fly-buck operates while this spike is over the I_LIM specified in the datasheet. They are assuming the spike have to be shorter than the blanking time of the UCC28881.

However, they would like to make sure that they have some margin for all operating points, However, there is nothing in the datasheet on the minimum duration of this blanking time. Would it be possible to have more information about it?

Thanks & Regards,

Pol

  • 0
    TI__Guru 73595 points
    The UCC28881 datasheet provides a typical LEB time about 250ns, page 14, Figure 14. tON_TO is 450ns based on the electrical table on page 6. The time is 200ns between LEB rising and tON_TO rising. So LEB time is 250ns.