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UCC28C43: PCN# 20221216002.1

Part Number: UCC28C43

Hello.

We've been using the UCC28C43DR regulator on our boards since many years. Now we have received the first reels of this component according to PCN# 20221216002.1

According to the PCN there should be no functional impact, but we noticed some differences, if we compare to the previous version of the component (before the PCN). These differences are not explained in the datasheet.

Furthermore, in the PCN we noticed that ‘Design change’ is selected.

Could you please explain in detail which are the differences from the old UCC28C43DR (prior to PCN) to the new UCC28C43DR (after PCN)?

  

Comparing the waveforms, the new UCC28C43DR switches off much more quickly.

With no load, the old UCC28C43DR works in burst-mode. The new UCC28C43DR is always switching.

Due to this, the input current of our converter (with no load) is more than double, using the new UCC28C43DR.

This test was made on the same board, with exactly the same components, only the regulator was replaced from old version to new version.

 

Pic01: drain of switching FET (flyback-stage)

White trace: old UCC28C43DR

Yellow trace: new UCC28C43DR

 

Attachment Pic02: drain of switching FET (flyback-stage), old UCC28C43DR, no load

 

Attachment Pic03: drain of switching FET (flyback-stage), new UCC28C43DR, no load

Thank you.

  • Hi,

    The differences per the datasheet specs are listed in PCN. A faster switching can be from variations from part to part but a corresponding sample still meets the specs. The IC has no burst mode operation. The pulse skipping is from COMP voltage low and resulted in CS threshold to close to zero so pulses reach their minimum or disappear. The new part your are using may have different COMP to CS offset compared to your old devices but COMP to CS offset is in a range (or called tolerance variations) so for same COMP voltage some parts can start to show no pulses while for some other parts (COMP to CS offset close to min the specs) pulses can still present.