I recently purchased some of the 33V, 3W shunt regulators along with some external 5ohm power resistors. I had hopes to use these to dissipate excess energy from my motor controller and keep my power supply from triggering over-voltage protection.
I attached my power resistor to one of the boards and placed it across my power supply (in parallel with the system I want to power). When the voltage reached the 33V shunt point, the regulator kicked in and began pulling a large amount of current compared to what the system regularly uses. It triggered the 5A OCP on my power supply which lowered the supply voltage to ~24V. The board also became quite warm. It appears this broke something, as now whenever I supply power (even far below the shunt point), the regulator draws current.
For context, my system is controlled to provide sinusoidal (1Hz) current to the motor. I am not sure the max current, but can find out if necessary. The voltage peaks last up to 500ms, I estimate that the system is moving around 70J of energy, and I’m supplying 29V.
My assumption was that if I populated an external resistor of sufficient power capability the board would be fine, but it seems like the resistor is not the limiting factor here. Is 500ms too long of a spike? Or is there some additional power restriction not related to the shunt resistors? I’d very much appreciate some help filling in any misunderstandings I have about the product, and determining whether it is possible to use this board for my use case!