New MOSFET with high breakdown voltage

[Old cart]

Just found this new MOSFET. Would it be useful in PI applications?
it has a rather high input capacitance so may require higher drive currents.


http://www.st.com/web/en/resource/te...2307.pdf#page9

[eclipse]

Somehow higher input capacitance as you noted, a dedicated gate driver can help, but has quite low output capacitance which is very good.
Good total gate charge, also quite high avalanche capabilities, will be enough to drive a coil without the need of a snubber circuit.
With such high resistance Rds of up to 2 Ohm it will be properly heating up it will need good heat sink for sure.
Might be worth testing to see any advantage of high voltage setup.

[kt315]

what applications you meant of?

reminder you, Eric in last his '10Ohm coil' schematics used low-voltage IRFD110/113 (BOOM... ahh... 0_o)
do you mean DELTA PULSE, DEEPERS, PULSE STAR, like some kinda the examples of deeper needed in high-voltage FETs?

[Old cart]

[QUOTE=kt315;210030]what applications you meant of?

No specific detector, just any that would benefit from having a higher breakdown voltage. I suppose this could include that runs a higher battery voltage or longer pulse width.
For example 300uH- 4 ohm total effective resistance, 12 Volt source, 500 ohm damping gives, I believe, about 1500 volt kickback.

[Davor]

Interesting, it also has a superb Idss.

[moodz]

...you really want something like this ...


http://www.cree.com/~/media/Files/Cr...2M1000170D.pdf


and there are much better devices available.

[eclipse]

It's not a direct replacement, needs Vgs -5/+20

[Old cart]

Moods, that looks like an impressive device too.

[kt315]

Drain-Source On-State Resistance 1.0 Typ. thats cool Moodz. but notice there is still not Fets with milliOhm DSOSR and with 1500-1700V D-S. reminder you that 'obtruhannyj mol'iu' (somebody translate it in english) IRF740 has 0,55 Ohm Max.

[green]

What performance increase should I expect using one of the mentioned high voltage fets compared to using a IRF740 with a MUR460 diode in series?

[Old cart]

kt315-Perhaps someone with a semiconductor background can explain it but I think in order to get high voltage you have to give up low resistance.

[eclipse]

I have designed such modification - 1KV @ 0.1R, though not tested yet
I've designed it to work as as drop-in replacement for any PI device,
will use this new front-end on multiple devices (replaces oscillator & transmit up to the point of opposite diodes connect to pre-amp) to see if there's any improvement.

[Davor]

What performance increase should I expect using one of the mentioned high voltage fets compared to using a IRF740 with a MUR460 diode in series?

A diode is not improving the high voltage performance. It simply screens the MOSFET's capacitance, making higher damping resistor possible, and consequently flyback faster.

You may cascode a pair of garden variety mosfets to obtain higher voltage.

[Tinkerer]

What performance increase should I expect using one of the mentioned high voltage fets compared to using a IRF740 with a MUR460 diode in series?

Higher Flyback voltage allows for more coil current or faster decay for the same coil current.

However, 1000V on the PCB, cable and connectors can be a problem.

[moodz]

True however the 740 has too much cap on gate. I run 5 ohm ccts 2 amp deviation 3.3 volt supply and 2 microsecond sampling after turnoff ...low ron is not most crritical factor.