Driver IC with variable dead time for inverting buckboost SMPS?

[Flyback]

Hello,
We are designing a +/-48V , 400W Power supply for a Class D, Bass guitar amplifier supply.
The +48V rail will simply be supplied by the output of an offline, 48V PSU bought off-the-shelf.
The –48V rail will be provided from the same +48V rail by putting it through an inverting buckboost converter as in the diagram and LTspice simulation below.
The problem is that we need it to be synchronous. (Use a FET across the output diode).
Normal synchronous controller IC’s are for synchronous buck or synchronous boost converters and can’t be used with inverting buckboost converters like we have here.
Therefore, we need an IC which will drive the power FETs and have a variable dead time, then we can add the gate drivers and gate_drive_isolators ourselves. Most of the relevant driver ICs have dead time which is far too short, and can’t be used with the external gate driver ICs that we will be using, since gate driver ICs have relatively long turn-on delay times which would result in overlap and “shoot-through”.
So do you know of eg a synchronous buck driver IC which has adjustable dead time? Such an IC could be used by us for this inverting buckboost.

 

[Flyback]

The attached SMPS is a Cuk converter and can give us 48V to minus 48V at 200w conversion, and does not need a transformer, however, it has a resonating problem.
That is , if the output load is pulsating at approx. 7600Hz (which is very likely with a class D audio amplifier load), then it will go into damaging oscillatory behaviour due to the resonant frequency of the L,L,C of the Cuk power stage.
LTspice simulation also attached.

 

[ronsimpson]

I do like Cuk converters but:......
Center Tapped Transformer (inductor).
I can change things to get -48 out if that is a big deal.
No regulation. The -47 will track the +48.

 

[ronsimpson]

So the real goal is +48V in -48V out.
L1,2,3,4 is the same coil/transformer.
Under heavy load there is about 1 volt loss across the PMOS transistors.
When MOSFET-1 is closed there is 47 volts across L2 and -47 on L3. I set L2,3 to 47turns so the math is simple.
L4 (1.5 turns) will add 1.5 volts to the negative stroke. The right end of L4 will be at -48.5 volts.


This is a trick I learned when I was designing TV sets. I would add one turn to a transformer to get just enough voltage to compensate for the drop of a diode. (or diode+transistor)