I'm using a DRV8412 to drive a RLC load at resonance (so it appears like a resistive load) with a fundamental of 40-100kHz. Originally when I chose that IC, I expected the maximum load impedance to be around 20-25 Ohm. However, it appears that depending on load conditions, it can vary between 10-50 Ohm.
I've considered using a step-up transformer, but that pushes too much current through the IC at low impedance. Switching 1:1/step-up might be reasonable (e.g. using a Coilcraft configurable transformer), but sounds like a headache to get right.
Other options I'm thinking of is redesigning with external FETs (thankfully I'm just using an EVM right now). Using resonance to add gain doesn't work due to my bandwidth requirements.
Any other ideas?