I've a situation where a string of 5 Leds (2mA) has to be powered from
48V up to 1kV (HV safety indicators). That's about 20mW for the leds, and 2W heat under 1kV.The system ATM is a simple CC source (1BJT + 2 mosfets) but we now need as less heat generation as possible and a more compact design.
The first idea was a resistive drop down to 50V or so, and from there have a small step down switcher current regulator providing the 2mA current. At 50% efficiency that would have been 0.8mA for 1.2W saving, and possibly more.
...but all the little switchers I could find either have huge current draw or low max input voltage, or something.
Before I start rolling my own, which seems not so simple (first attempts show a serious lack of 'efficiency') I have to ask if I missed the good IC? (or idea)