Please find the schematic below. Can an electronic expert explain to me the exact function. Input is ~300VDC at R7. The unit works as expected and smoothly ramps up to 280VDC in about 5-6s, nice. The R7/C7 (R10/C8) function I do understand, it’s time delayed charge of the capacitors which slowly starts the conduction of the regulator mosfets. What is the function of D4/D5 and R9?
Q2: I setup a simulation on LTSpice which stops with a Too Small Time Step, blah, blah, blah after 5.8s. Any advice about the correct LTSpice settings. I suspect this behavior has something to do with the zeners…
Simulation file attached.
Q2: I setup a simulation on LTSpice which stops with a Too Small Time Step, blah, blah, blah after 5.8s. Any advice about the correct LTSpice settings. I suspect this behavior has something to do with the zeners…
Simulation file attached.
I'm not the brightest bulb here but this is a capacitor multiplier.Zenners are for Gate-drain voltage protection( usually 12..18v zenners) .r9 and r7 sets a voltage for the first gate with t9 discharging the first gate after shut down alowing also for a predictable slow start startup.
Zenners could be replaced with fixed dc voltage sources with r series around 10 ohms but I suspect your mosfets need a 12...18 volts zenner as for the sim to work try also a generic mosfet instead a specific one if the 18v zenner doesn't do the job.
Zenners could be replaced with fixed dc voltage sources with r series around 10 ohms but I suspect your mosfets need a 12...18 volts zenner as for the sim to work try also a generic mosfet instead a specific one if the 18v zenner doesn't do the job.
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