flatfootskier
Member
I have rectified & smoothed 150V DC. I want to insert current limiting, I've tried an LM338 with a 1 Ohm 10W resistor connected between Adj & Out, connecting the load to the Adj pin.
As I understand it, the 338 should always maintain 1.25V across the resistor so my current should be limited to 1.25V/1 ohm = 1.25A
I've tried it once & it announced its disapproval by sending smoke signals rather promptly. Before it even had a chance to transfer any heat to the heatsink. So I don't believe the root cause is thermal.
I'm aware that the LM338 has a max of 32V, but I have no ground connection to it, so to my mind, with it floating, it's only exposed to the differential voltage between its input & output.
Would appreciate any guidance. Thanks.
As I understand it, the 338 should always maintain 1.25V across the resistor so my current should be limited to 1.25V/1 ohm = 1.25A
I've tried it once & it announced its disapproval by sending smoke signals rather promptly. Before it even had a chance to transfer any heat to the heatsink. So I don't believe the root cause is thermal.
I'm aware that the LM338 has a max of 32V, but I have no ground connection to it, so to my mind, with it floating, it's only exposed to the differential voltage between its input & output.
Would appreciate any guidance. Thanks.