Hi (Greg?), Using the datasheet for the PMOS transistor you use in your circuit, how do you calculate the value of R116 (the resistor between +200V and the source of your MOSFET)?
On Saturday, March 25, 2017 at 12:30:53 PM UTC-4, gregebert wrote: > > That's basically what I use in my designs. I'll highlight the differences: > > - I use a PMOS instead of PNP, mainly because it requires no > drive-current. > - R1 & R2 are replaced with a pot to make the current adjustable. > - The above pot can driven from a small DC-DC converter (my > preference), or between the HV supply & GND. There's essentially zero > current for PMOS gate-drive, so high resistance values are fine. Not the > case with PNP, though, due to finite base-currrent. > - A zener diode is added to clamp any spikes that may arise at the > gate of the PMOS device. It's a paranoia item. > - A filter cap was added, in case there is unexpected noise from the > DC DC converter, and also to suppress any very-short transient that may > arise that are too fast for the zener to kick-in. (paranoia item). > - A large resistor across the PMOS to bleed any potential ESD. Without > it, there is a remote possibility of charge-buildup. (paranoia item) > > So, this circuit is replicated for each anode. When multiple anodes are > driven, they all share the same gate-drive signal, which I call PDRV on the > attached schematic. > > > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/51d0a30b-a31a-4331-8222-babb2654b502%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
