My goal is to drive a beefy solenoid (1.6 Ohm / 1.5 mH / 50ms actuation time, once every 1-2 seconds) from a 36mF (3x12mF in parallel) capacitor bank at 24V, charged from an 1A PSU. This capacitor/low power PSU arrangement was chosen to limit the coil heating in the event of a failure.
The main problem is limiting the inrush / charge current. Possible solutions:
- Current limiting resistor (10 Ohm): Produces a lot of Heat (10W), slow (2sec)
- NTC Thermistor: Way to long cooldown time (60+s)
- Transistor based: Voltage drop is undesirable, and they seem to produce a lot of heat
- Inductor: might cause ringing
- LED constant current power supply (for instance PLM-25-1050): they all feature short-circuit-protection, which would likely trigger
- Soft start ICs: Soft start time is <10 ms, which is not enough
The only viable solution I can think of would be using a constant-current boost converter from 5V which doesn't care about "short circuits".
Do you have any other ideas? Is there an example / premade boost-converter? I cant seem to find a component matching my requirements.