Yes you are right but I want to use the gate driver because for two reasons
with the 555 the signal deasappear once the Vin is larger than 7.5V
my device needs Ig abaout 1A to swich correctly and the 555 is not able to delivre such a current

The 555 could drive 200mA into the base of your switching transistor. If that transistor had a beta of 5, you'd Ic would be an amp. If you need more drive current, use a darlington instead of a single transistor.

If you're timer won't work with Vin > 7.5V, check your circuit and the timer; any voltage between ground and VCC should work.

 

So you think the IRS211 will do it?
What IS the output device?
Max.

 

So you think the IRS211 will do it?
What IS the output device?
Max.

http://docs-europe.electrocomponents.com/webdocs/0dbf/0900766b80dbfe89.pdf
IGBT Qg 48nf
tdon 18ns
tdoff 27 ns

Do you agree with the Ig current ?

 

Hi kanoun,

Why don't you just drive the transistor controlling the relay directly from the 555 timer? The timer can sink/source 200mA.

The bipolar 555 can, can't remember offhand the limits on a CMOS 555.

The squarewave output from the CMOS 555 should get closer to the rails, but it could struggle with the gate capacitance if much switching speed is called for.

 

The bipolar 555 can, can't remember offhand the limits on a CMOS 555.

The squarewave output from the CMOS 555 should get closer to the rails, but it could struggle with the gate capacitance if much switching speed is called for.

So you confirm the fact that I need a driver. One more point: could you help to choose the right driver for my application

 

So you confirm the fact that I need a driver. One more point: could you help to choose the right driver for my application

No, we're not mind readers. No one can confirm your requirements until you state your problem more clearly. Are you using a CMOS 555? Is there some reason why you can't use a regular 555? Regardless of which type of timer you're using, all you need is a voltage high enough to turn on the NPN transistor. If the timer you choose can't do that (bad choice), you can use a darlington to increase current gain in the switch.

As always, it's easier for others to help you if you can clearly articulate what you want.

 

http://docs-europe.electrocomponents.com/webdocs/0dbf/0900766b80dbfe89.pdf
IGBT Qg 48nf
tdon 18ns
tdoff 27 ns

Do you agree with the Ig current ?

Wow, 48 nF gate charge! No wonder you need a driver. If you are just turning on a relay once a day, it doesn't matter, but if you are trying to do some sort of PWM to control the power to your load, you want to switch quickly, and that implies huge currents. I don't really have experience with IGBT's, but with MOSFETs, if you drive them too gently, they will stay in the linear region too long, and get hot.

Looks like all you need is low-side drive. I use the MIC4451/4452. You might want to take a look at that part, or similar ones made by other manufacturers.

One final tip, put a good ceramic bypass capacitor between the power pins of your driver chip.

 

Is 48 nF supposed to be a charge or a capacitance. The reason I ask is because charge is measured in Coulombs and capacitance is measure in Farads. The relationship between charge and capacitance is
Q(Coulombs) = V(volts)*Capacitance(Farads)

When people are talking about stuff they really should try to get the units correct, or is there some conventional "under the hood magic" going on here?
EDIT: No magic. The datasheet uses the correct units which are nC, so 48 nC, is a maximum value with 35 nC being the typical.

@kanoun
BTW you never did show us how you got the 1A current requirement for proper switching. How did you do that?

The simplest of first order approximations is:
Since 1 Ampere is 1 Coulomb/sec it should take 1 second at 1 ampere to charge or discharge 1 coulomb. Therefore it should take 48 ns. to charge or discharge 48 nC with a 1 Ampere sink or source. Is that what you are saying you want to do?

Of course real life and complex switching requirements are always a challenge, but it helps to be in the right ballpark.

 

Is 48 nF supposed to be a charge or a capacitance. The reason I ask is because charge is measured in Coulombs and capacitance is measure in Farads. The relationship between charge and capacitance is
Q(Coulombs) = V(volts)*Capacitance(Farads)

When people are talking about stuff they really should try to get the units correct, or is there some conventional "under the hood magic" going on here?
EDIT: No magic. The datasheet uses the correct units which are nC, so 48 nC, is a maximum value with 35 nC being the typical.

....

Yes, you're right. I wasn't thinking 100% when I propagated the typo. Should be nC.

 

The better question is why the TS/OP made the original typographical error.

 

Is 48 nF supposed to be a charge or a capacitance. The reason I ask is because charge is measured in Coulombs and capacitance is measure in Farads. The relationship between charge and capacitance is
Q(Coulombs) = V(volts)*Capacitance(Farads)

When people are talking about stuff they really should try to get the units correct, or is there some conventional "under the hood magic" going on here?
EDIT: No magic. The datasheet uses the correct units which are nC, so 48 nC, is a maximum value with 35 nC being the typical.

@kanoun
BTW you never did show us how you got the 1A current requirement for proper switching. How did you do that?

The simplest of first order approximations is:
Since 1 Ampere is 1 Coulomb/sec it should take 1 second at 1 ampere to charge or discharge 1 coulomb. Therefore it should take 48 ns. to charge or discharge 48 nC with a 1 Ampere sink or source. Is that what you are saying you want to do?

Of course real life and complex switching requirements are always a challenge, but it helps to be in the right ballpark.

It is nc actually ... All what I did is IG = QG/tdON

 

Is 48 nF supposed to be a charge or a capacitance. The reason I ask is because charge is measured in Coulombs and capacitance is measure in Farads. The relationship between charge and capacitance is
Q(Coulombs) = V(volts)*Capacitance(Farads)

When people are talking about stuff they really should try to get the units correct, or is there some conventional "under the hood magic" going on here?
EDIT: No magic. The datasheet uses the correct units which are nC, so 48 nC, is a maximum value with 35 nC being the typical.

@kanoun
BTW you never did show us how you got the 1A current requirement for proper switching. How did you do that?

The simplest of first order approximations is:
Since 1 Ampere is 1 Coulomb/sec it should take 1 second at 1 ampere to charge or discharge 1 coulomb. Therefore it should take 48 ns. to charge or discharge 48 nC with a 1 Ampere sink or source. Is that what you are saying you want to do?

Of course real life and complex switching requirements are always a challenge, but it helps to be in the right ballpark.

I guess the problem is well explained .,. I m using the setup I attached and I'm asking whether the driver connection is ok or not ... I'm also asking how to chose the right driver for switching measurement. The ne555 is a bipolar one but I will remove it because I want to learn how to use a driver and why we do so. Many thanks for your help

 

Is 48 nF supposed to be a charge or a capacitance. The reason I ask is because charge is measured in Coulombs and capacitance is measure in Farads. The relationship between charge and capacitance is
Q(Coulombs) = V(volts)*Capacitance(Farads)

When people are talking about stuff they really should try to get the units correct, or is there some conventional "under the hood magic" going on here?
EDIT: No magic. The datasheet uses the correct units which are nC, so 48 nC, is a maximum value with 35 nC being the typical.

@kanoun
BTW you never did show us how you got the 1A current requirement for proper switching. How did you do that?

The simplest of first order approximations is:
Since 1 Ampere is 1 Coulomb/sec it should take 1 second at 1 ampere to charge or discharge 1 coulomb. Therefore it should take 48 ns. to charge or discharge 48 nC with a 1 Ampere sink or source. Is that what you are saying you want to do?

Of course real life and complex switching requirements are always a challenge, but it helps to be in the right ballpark.

Yes that is what Im saying basically

 

now could you answer

I still don't see where you stated which version of the driver you have.

 

I still don't see where you stated which version of the driver you have.

The one with 9v ... It is working know ... Shame on me ... Could you help for the other questions ?

 

It is nc actually ... All what I did is IG = QG/tdON

See that is the problem. You throw a complex datasheet at us and a formula and expect us to know which numbers you have selected from that complex datasheet to arrive at your results. Well I can't duplicate your results and I'm just a poor old country boy who's not as smart as you and I'm from Missouri so you're just going to have to show me. None of the choices in the datasheet correspond to 1 Ampere as the required current to achieve a desired switching time of how long?

 

See that is the problem. You throw a complex datasheet at us and a formula and expect us to know which numbers you have selected from that complex datasheet to arrive at your results. Well I can't duplicate your results and I'm just a poor old country boy who's not as smart as you and I'm from Missouri so you're just going to have to show me. None of the choices in the datasheet correspond to 1 Ampere as the required current to achieve a desired switching time of how long?

I'm not asking for that I'm just asking wether this reasoning is the wright one ... I took the QG whitch is 45 nc and the tdON is about the same 45 ns

 

Well that is the problem. In the datasheet I'm looking at Qg is 35 nC typical and 48 nC maximum. The tdON is 18.5 ns typical. So no I don't agree with your reasoning or your mathematics. I also want to know if you are working with 390 Volts Vcc and 7 Amperes of collector current which are the stated conditions for the measurement. If you are doing something else then you have to question the use of the numbers for tdON. Should it be more or less if your Vcc is 60 Volts and your collector current is 2 Amperes.

 

Well that is the problem. In the datasheet I'm looking at Qg is 35 nC typical and 48 nC maximum. The tdON is 18.5 ns typical. So no I don't agree with your reasoning or your mathematics. I also want to know if you are working with 390 Volts Vcc and 7 Amperes of collector current which are the stated conditions for the measurement. If you are doing something else then you have to question the use of the numbers for tdON. Should it be more or less if your Vcc is 60 Volts and your collector current is 2 Amperes.

You are right I just confused with another datasheet but if it were the case (45nc and 45ns) would the reasoning be good

 

Yes, for the reason I stated in post #28, and if the other conditions on Vcc and Ic, that define how the measurement was made, are satisfied. If the conditions of the measurement are not satisfied than the value for tdON and the calculation are meaningless.