I need a power supply that can deliver stable 370 V DC voltage, while load resistance is variable.
Average load current(assuming stable 370 V supply) is 200 mA, however it may rise to 400 mA. Input voltage(DC) is 40 - 60 V higher than 370 V, but it's unstable.
I was expecting that I would simply buy something like LM317, but rated for 370V and 400mA. It quickly turned out that nobody sells such things.
Closest to what I need was this stabilizer: Microchip LR8K4-G, 1.2 → 440 V Linear Voltage Regulator, 30mA, 1-Channel, Adjustable, ±5%.
It meets my voltage requirements, but it can only handle 30 mA.
This fragment from its datasheet caught my attention:
The output voltage can be adjusted by means of two external resistors, R1 and R2, as shown in the typical application circuits. LR8 regulates the voltage difference between VOUT and ADJ pins to a nominal value of 1.20V. The 1.20V is amplified by the external resistor ratio R1 and R2.
So if we can just amplify the voltage difference, then perhaps there is a way to use lower voltage stabilizers for higher voltage? Can somebody point me in right direction?