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UCC27282: UCC27282DR For Full-Bridge buck-boost Design

Part Number: UCC27282


We design a 4 N-MOSFET full bridge buck-boost with two UCC27282DR.

The UCC27282DR's VDD=12V,

Even if both UCC27282DR's HI and LI are low,HO and HS still have about 7V output,is this right?

How to make VOUT=0V when HI and LI are low?


  • Hi Wenxing,

    The VOut is the output capacitor of your full-bridge circuit. Can you measure HB-HS, HO-HS, and HS-GND on your UCC27282 devices and record the results?
    We can expect the behavior of the devices to have a reading of 0V measuring across HO-HS when the HI is set low.



  • Hello Jeremiah,

    Yes,the Vout is full-bridge circuit output. Now HS=7V ,so Q3's source pin=7V, then it will make vout=7V by Q3 body Diode.

    When HI=LOW, the results measured is HO-GND=7V,HS-GND=7V, HO-HS=0V,HB-HS=5V.


  • Hi Wenxing,

    Thanks for providing the measurements. I can see you've confirmed HO-HS = 0V. Is this reflective of the answers you were looking for (since I did not see any follow-up question)?



  • Hi Jeremiah,

    Thanks for your answer!

    That meas "HS-GND=7V when the VDD=12V and HI=0V" is normal result for UCC27282 ?

    If so,the HS's 7V will lead to Vout=7V by Q3's body diode.

    So My question is:

    If VDD=12V,HI=0V, HS-GND=7V is normal UCC27282 status?


  • Hi Wenxing,

    The potential difference seen in HS-GND can be attributed to the inductor connected to the HS node. This behavior can be expected as the inductor discharges when HI=0V, and this is aligned with the UCC27282 when used in an application like this.