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UCC28070 - DC Bus Drops Drastically from 400V to 200V

Arun Soman
Intellectual 400 points
Other Parts Discussed in Thread: UCC28070

 Hi ,

We build 3kW Interleaved PFC works from 90-265V AC and it is Working Fine

.Now the requirement has come to Work form 120V Battery.

When I feed 120V DC to the input of the rectifier, it is Able to Boost to 400V. When we load 2.6kW in the Following Pattern the DC Bus Drops Drastically from 400V to 200V.

Is there any way we can make UCC28070 as Only Boost Converter with High Band Width (without PFC) so that The DC Bus Will not drastically.

Can anybody help me to find What are the Changes to Be done on UCC28070 Schematic to make Suitable for DC Input


Thanks in advance.

  • 0
    TI__Guru* 85616 points

    This device needs to see a rectified sine wave at VINAC to work correctly. Page 23 of the data sheet discusses this.  This device was really not designed to a control a boost with a DC input.  However, some customers have had success by feeding VINAC with a square wave with the low period being 200 to 300 us at 200Hz switching frequency.  Also if the VINAC dv/dt is too fast it will not trigger the correct KVFF level.  The VINAC pin needs a dv/dt no more than 75mV/us.

    Regards,