UNiversal MOSFET Gate drivers

[alanlts]

" in recent years, MOSFET has been widely used....but different MOSFET need different voltage to drive it ON. Now my final year project is to come out with a universal MOSFET gate drivers that will drive ALMOST all kinds of MOSFETs"

now i have no confidence in getting it done...i just have some ideas bits here and there...

1) is it possible to drive the Mosfet's gates with "555 multivibartor" or "CMOS circuit". but which circuit is better?

2) do i need a control circuit so that it will detect the needed voltages?

I would really like some suggestions and advice...

thank you

desperates,
alan
:?

 

[Oznog]

Frankly I don't understand what you're trying to do at all. MOSFETs require drivers in certain circumstances, but the driving task is particular to the circumstances of the circuit. Speed is often a critical question.

Most MOSFETs switch on fine on 5v logic, no driver needed if the source is a positive or negative rail. Sometimes 5V is not enough or the source is outside the rails, but again the circumstances could be anything. "Universal" is not workable, you need a specification detailing what you want to do.

The 555, "CMOS circuit", and voltage detection don't make much sense.

 

[sae140]

A "universal MOSFET driver" ? I'm not sure there could be such a thing ...

For many simple DIY circuits, a 555, TTL with level shifting, or a CMOS logic gate will directly drive a MOSFET gate ok .... but problems arise when you start to address more demanding applications.

With power MOSFETs for example, it's desirable to have some form of active pull-up and pull-down to ensure that the gate voltage rises quickly from it's switching threshold (of often around 3 volts) to a safe operating level of typically 10 volts or more.
It's also desirable to opto-isolate the logic signal from the gate driver, in order to simplify circuit design. Commercially-available driver chips address both of these requirements. But then these driver chips will require some form of floating power supply, involving either multiple transformers or extra secondary windings.

In switching circuits which present a predictable 'off' period (oscillators etc), it *is* possible with some ingenuity to employ the voltage between source and sink to power discrete drive circuitry, thus eliminating both driver chip and it's power supply requirement, but even this will not work for extended 'on' periods (and so cannot truly be considered a 'universal' MOSFET driver cct.) and anyway, opto-isolation becomes essential in this particular case.

The big problem with using opto-isolators is that they are relatively slow devices (turn-on/off speed typically 5 to 25 uSecs), which may be tolerable in low-frequency power circuits, but would be unacceptable in high frequency applications, which require a completely different approach to driving gates.

Hope the above gives you a flavour of the different problems which present themselves. Sadly I consider your idea of a universal MOSFET driver to be over-optimistic.

Regards

Colin