Hi,
I am already using the L6599 as a HB LLC controller and I am trying to achieve higher output powers, however my input supply voltage is only ~30V. Already primary side currents are high. In order to bring these to realistic levels I really should use a Full Bridge topology.
My question has multiple elements:
- Has anyone used either the L6599 or L6699 to drive Full Bridge? I have simulated this using the L6599 and a set of low propagation delay external gate drivers and it seems to work. But this is clearly a non-standard configuration. Has this ever been done in the real world?
- I did these simulations by creating my own behavioural model of the L6599. In the process of developing the model there are a few assumptions. An important one being that the OUT pin of the L6599 is indeed only ever used as the current return path for the high side gate driver. If this is true, then simply by only supplying the boost PIN with VCC and not connecting the OUT pin to the SW node, it should be possible to use the L6599 to drive external ground referenced high and low side drivers to create Full Bridge. Can this be confirmed?
- In the L6699, it is not quite so simple as from my understanding the L6699, uses the signals seen on the OUT pin to derive information necessary to achieve adaptive dead time. If this is so, then by not using the IC as designed and any attempt to use external gate drivers would negate the adaptive timing.
I feel I am trying to make a square peg fit into a round hole. Am I wasting time and effort trying to get these LLC controllers to operate as Full Bridge controllers. I have had great success with the controllers and results have been very reliable. Before I move to a different topology (PSFB), I would like to exhaust these possibilities and see if others have ever done what I am attempting.
All the best
Aidan
