Very long dead time produces a characteristic type of distortion. You can make this very obvious by playing a pure tone in the low or midrange area and increasing the volume slowly from 0.
I am currently thinking about inverter circuit for IR2011...What would be prefered circuit...Drive it with:
1.LT1016 directly
2.Use LM311 and CD4069
3.Use LM311 and Transistor inverter
Thanks
1.LT1016 directly
2.Use LM311 and CD4069
3.Use LM311 and Transistor inverter
Thanks
IR original design does not have deadtime circuit incorporated in their design at all using IR2011S.
Is it really necessary?
Is it really necessary?
Hi
It depends on how good are your fets... if they are fast + fast diode then you don't need it, but if you use fets like I did, then you will need it
It depends on how good are your fets... if they are fast + fast diode then you don't need it, but if you use fets like I did, then you will need it
Luka,
i have a plan to use IRF540 's (2X) in output with 50ohm gate resistors in parallel with 4148 diode.
i have a plan to use IRF540 's (2X) in output with 50ohm gate resistors in parallel with 4148 diode.
So Luka ,
Are we talking about resistor-diode dead-time on gates of output MOSFETS or circuit on input of driver (IR2011)?
IRF540 -do I need one for these MOSFET's?
Are we talking about resistor-diode dead-time on gates of output MOSFETS or circuit on input of driver (IR2011)?
IRF540 -do I need one for these MOSFET's?
Depending on the amount of gate charge and on the particular components added between the outputs of the driver and the gates, you may easily find that those IR ICs actually provide too much dead time.
Eva said:
Hi Eva! In electronics, everything works in the same way. The so-called mathematics. The MOSFETs also have Ft, despite you classified it for bipolar transistors. So there's another limiting factor for switching speed.
Apsolutely,
MOSFET transistors have Ft.
Eva is really good person that knows a lot about switching aplications but needs to get some more informations about some certain things.
MOSFET transistors have Ft.
Eva is really good person that knows a lot about switching aplications but needs to get some more informations about some certain things.
You are both right. MOSFETs do have an Ft defined (see Baliga), which is a function of the internal gate resistance Rg, but usually it is not relevant to high-speed switching applications. Parasitic inductance in the source lead is an inherent limiting factor for voltage-drive gate drives. Generally, one desires to limit the speed of the MOSFET via external gate resistance, since relying on the source inductance is dangerous to devices!
The inherent response speed of the channel for Si-based vertical power MOSFETs is less than one nanosecond. Metal-gate MOSFETs can switch in a few nanoseconds, poly-Si gates in 10-20 nanoseconds. You should not use these types of speeds unless you know what you are doing, or don't mind smoking a lot of parts while you learn.
In general, what you gain by going to extreme switching speed, you lose with EMI problems and voltage overshoot. You can get away with more at low voltages, and less at high voltages. A low inductance package will also let you get away with more.
Ciao,
John
The inherent response speed of the channel for Si-based vertical power MOSFETs is less than one nanosecond. Metal-gate MOSFETs can switch in a few nanoseconds, poly-Si gates in 10-20 nanoseconds. You should not use these types of speeds unless you know what you are doing, or don't mind smoking a lot of parts while you learn.
In general, what you gain by going to extreme switching speed, you lose with EMI problems and voltage overshoot. You can get away with more at low voltages, and less at high voltages. A low inductance package will also let you get away with more.
Ciao,
John
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