UCC24624: Question about UCC24624

Hi Bastian,

Please see below

1- Is it possible to put several MOSFETs in parallel for this chip?  If so, what do you recommend? 

The UCC24624 uses VDS sensing to drive the gate with proportional gate drive. It is not easy to do this with parallel FET's. See older E2E post on the same here: ttps://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/977117/ucc24624-paralleling-2x-ucc24624s?tisearch=e2e-sitesearch&keymatch=ucc24624%252520parallel# 

2- Can the chip be powered at 28V (Absolute rating)? If not, would a linear regulator with a bipolar for 15V suffice?
You would want to clamp VCC to less than 28V. Here is another E2E post on the same e2e.ti.com/.../ucc24624-extending-vd-voltage

3- The component measures the drain-source voltage of each MOSFET to rectify the secondary. Does this mean it's autonomous in terms of rectification and totally independent of the primary part? As well as from the compensation? Does he manage dead-time alone ? 
Yes, the SR controller runs independent of the primary controller. This has fixed on and off time blanking to help minimize the chance of false triggering on noise. 

4- My application: Vin: 400VDC; Vout: 28V; Iout: 50A. I'd like to make a first prototype using diodes (low power use < 400W), then implement the synchronous rectifier circuit with MOSFETs doubled in each arm. The chip used would be the UCC256403 with this component. 

Have you seen the newer UCC256603?

 Although you recommend a PSFB for this type of power, I've had bad feedback from your competitor (Analog Device) on the use of this converter topology. I'd like to start with this type of converter, as it can be driven as a half-bridge, and I have experience of parallel resonance (making a resonant inverter). So I don't think I'll have any difficulty in making a series resonance.
For 400W, either LLC or PSFB can be used. We typically recommend half-bridge LLC up to around 1kW but this is not a function of the controller. It has more to do with component stress. 

5- Do you have a demoboard where I could apply this use case?

We do not currently have an EVM at this power level but PMP31179 is very close to your application. 

I hope this answers your questions. 

HI Bastian,

You're welcome. Here is the link to the UCC256603. 

Here is a simple comparison between the older and newer controller:

I hope this answers your question.