Other Parts Discussed in Thread: UC1708-SP
I am trying to build a push pull isolated DC/DC converter. Vin 26-34V, Vout 28V, Iout 10A. I am not opposed to using two converters to share the load using the Sync pin. My use case if for a satellite in LEO orbit and would like to keep most of my part selection to rad tolerant or HiRel if possible.
I am trying to understand the input voltage requirements for the IC since the converters input voltage will be higher than the ABS max of the controller. I noticed that the current draw was very small when using a gate driver which is what I intend to do. Can you simply use a resistor divider to power the IC from the main power line? Would this flow into an internal LDO and reject most of the noise? I know it is not the most elegant solution, but would you recommend an external LDO? I did not find a rad tolerant LDO that had an input voltage up to 34V.
As I mentioned above, I was leaning on using a gate driver to drive GaN FETs. Is there a specific rad tolerant gate driver you recommend for this particular application where both are low side FETs in the push pull configuration? I was looking at UC1708-SP which seems to do the trick, but was curious if I should investigate another one as well.
For the Synchronous FET driver application what isolation IC family would be best? As I understand, traditional opto-couplers have a disadvantage when put in space environments.
I also was curious about the isolation technique for the voltage feedback. Is there a specific IC family that you recommend there as well?
My last question regards the current sensing circuit. In the datasheet a sense resistor is used vs in the push pull calculator excel sheet a current transformer is depicted in the schematic. Does this controller prefer one over the other or does it mainly depend on the amount of current being sensed. Low current leaning towards the sense resistor method and high current to the transformer method. A follow up would be what sense resistor value would be considered small enough to extend the range current range of the current sensor, but large enough to reject enough noise.
