UCC27282: UCC27282DR For Full-Bridge buck-boost Design

wenxing zheng

Prodigy 50 points

Part Number: UCC27282

Hello,

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?

Thank!

5 months ago

0 Jeremiah Vo 5 months ago

TI__Intellectual 1340 points

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.

Best,

Jeremiah

0 wenxing zheng 5 months ago in reply to Jeremiah Vo

Prodigy 50 points

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.

Thanks

0 Jeremiah Vo 5 months ago in reply to wenxing zheng

TI__Intellectual 1340 points

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)?

Best,

Jeremiah

0 wenxing zheng 5 months ago in reply to Jeremiah Vo

Prodigy 50 points

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?

Thanks.

0 Jeremiah Vo 5 months ago in reply to wenxing zheng

TI__Intellectual 1340 points

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.

Best,

Jeremiah

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UCC27282: UCC27282DR For Full-Bridge buck-boost Design