On Tue, Apr 1, 2025 at 11:23 AM, eetech00 wrote:
Is the 1 ohm resistor the load?
It is part of what makes it a current regulator.? The LM317 drives its output pin until the voltage between its OUT and ADJ pins is 1.25 V which is its internal "reference" voltage.? If the ADJ pin was connected directly to the downstream end of the 1 ohm resistor, it would source 1.25 Amps.? But there is the 402 ohm resistor between the downstream end of the 1 ohm resistor and the ADJ pin, and we know there is (approx.) 1 V dropped across that resistor due to the current through the MOSFET, so that leaves 1.25 - 1.0 = 0.25 V across the 1 ohm resistor.? Hence, the LM317 drives 250 mA from its OUT pin.? A small amount of it (2.5 mA) also flows through the 402 ohm resistor to the MOSFET, but the bulk of the current (247 mA) continues to the string of diodes = the load.
?
Andy
?
