MOSFET gate drive circuit

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ee01akk

Joined: 23 Nov 2003
Posts: 23

08 Dec 2003 19:56 mosfet gate drive circuits

Hi,
I am trying to find a mosfet gate driver design that I can use in PSpice simulation. Are they only available as i.c's or does anyone have a specific design? I am trying to use the mosfet as a switch in a dc-dc boost converter.
Thanks for any help that you can provide.

flatulent

Joined: 19 Jul 2002
Posts: 4875
Helped: 324
Location: Middle Earth

08 Dec 2003 22:01 mosfet gate drive circuit

One common circuit is to use HC series gates. One way is to use the 74HC49 or 50 with all six gates in parallel. This will provide you with about 1 A peak current drive to charge and discharge the MOSFET gates. This only works in the real world if all of the gates are in the same IC package so that their time parameters all match.

You can also use the voltage controlled voltage source which has infinite output current capacity. Put a few ohm resistor between the output and your gates to limit the current. This will probably give you an overly idealized simulation result because of the idealized gate drive rise time.

goodboy_pl

Joined: 12 Mar 2002
Posts: 243

18 Dec 2003 2:10 mosfet gate driver circuit

usually Mos Gate Drivers are simulated by subcircuits and voltage controlled voltage sources + a little dealy (can be produced by RC and and ideal and gate) for dead time simulation.
u can produce tis subcircuit yourself in pspice or other spices and use datasheet of the driver for proper output impedance or dealy of theMGD.
also some manufacturers like intersil provide this subcircuits for their products.

BEST!

henrik2000

Joined: 06 Jul 2001
Posts: 109
Helped: 1

28 Dec 2003 23:52 using qc for gate drive design

Hi.. You could use MosFET drivers which are specifically design to do the job. Linear techbology has very good one for N or P channel FETs.
linear.com

International Rectifier has very good one too..

Makes your work easy and a finished reliable product.

Regards

rauol

Joined: 02 Oct 2002
Posts: 363
Helped: 11

01 Jan 2004 9:41 mosfet drive circuit high-side

There are many manufacturers of mosfet drivers But driving a power Mos is a tricky affair the points to be considered are the Input capacitance(Ciss), the frequency and the Total Gate charge(Qc) and the power handling capacity of the driver IC
Visit www.micrel.com and Elantec(taken over by Intersil)
if your switching frequency is below 2000 Hz you dont require a dedicated Mosfet driver,a Totem pole driver using one NPN and One PNP transistor is enough for which SPICe models are already available Rolling Eyes

alphi

Joined: 23 Dec 2001
Posts: 440
Helped: 1

02 Jan 2004 1:18 drive ckt for mosfet

maybe it help for you

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boram69

Joined: 06 Jan 2002
Posts: 54

02 Jan 2004 3:11 irf+fet gate driver

Happy New Year!
Upper File download from : http://www.ixys.com/tecnot01.html

barrybear

Joined: 22 Nov 2001
Posts: 268
Helped: 6

02 Jan 2004 10:26 mosfet half bridge gate driver spice model

I can understand your choice in using a mosfet design. You may have problems though as the mosfet switches very quickly and can produce noise ( spikey). I have found that a bipolar transistor switch especialy where inductors are used is a beter option.

Barrybear

MSH

Joined: 08 Dec 2003
Posts: 46

03 Jan 2004 16:40 mosfet gate driver circuits

In www.irf.com you can find the best article for Mosfet driver.

arcaphill

Joined: 17 Dec 2003
Posts: 89
Helped: 1

24 Dec 2004 3:47 gate drive circuit

Remember, add a dumping resistor 2-5 Ohm at each MOSFET gate

arcaphill

Joined: 17 Dec 2003
Posts: 89
Helped: 1

03 Jan 2005 7:07 driving mosfet pnp transistor fast discharge

Look it!

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poseidon_gal

Joined: 15 Dec 2004
Posts: 7

25 Feb 2005 17:30 mosfet capacitance ciss frequency

need help!!! i am driving my MOSFET at 290KHZ. Using IR2110 as my gate driver.

At low frequency, my high side waveform looks good.. it is a square wave. But as the frequency increase, my high side waveform start to look distorted. why is it so? is there a way to solve this problem??

Another problem is, i am using supply voltage of 15V. As i switch my MOSFET at 290KHz, my gate driver gets heated up easily. In less than 10 mins, the IC becomes very hot and i got to off my circuit. Is there any way to reduce the temperature? I cant use a heatsink coz it is a IC chip.

jzaghal

Joined: 31 Jul 2001
Posts: 219

25 Feb 2005 18:43 mosfet ckt

Hi,

At high frequencies the Mosfet's gate capacitance become significant.

We usually use IGBt's at this sort of high switching frequencies.

Hope this helps you.

Bye.

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25 Feb 2005 18:43 Ads

poseidon_gal

Joined: 15 Dec 2004
Posts: 7

25 Feb 2005 19:26 mosfet gate driver circuit+pspice simulation

sigh..i already build the circuit..there is no way for me to change to IBGT now.. is there any way i can reduce the effect of the gate capacitance??

If it is due to gate capacitance of MOSFET, how come it only affects my high side? there isnt any effect on my low side.

Added after 31 seconds:

sigh..i already build the circuit..there is no way for me to change to IGBT now.. is there any way i can reduce the effect of the gate capacitance??

If it is due to gate capacitance of MOSFET, how come it only affects my high side? there isnt any effect on my low side.

jzaghal

Joined: 31 Jul 2001
Posts: 219

25 Feb 2005 19:33 mosfet gate driving circuit

Hi,

Try using a lower frequency in the first place, something upto 100khz

is fine with mosfets.

Good Luck.

JuergFrefel

Joined: 26 Feb 2005
Posts: 4
Location: Southern California

26 Feb 2005 8:05 mosfet irf 440 driver matching+pdf

What kind of gate resistor are you using. The power consumption of the FETdriver depends to a large degree on how much current you drive the Gate with.
If you know what the gate charge of your FET is you can easily calculate the rise and fall time and see if you can increase the gate resistor.

Are you using a IGBT or MOSFET? Not many IGBT like to be switched at such a frequencies.

poseidon_gal

Joined: 15 Dec 2004
Posts: 7

26 Feb 2005 8:19 mosfet gate drive

i can't reduce my frequency as the half bridge (i using MOSFET to work as half bridge) is connect to a load that requires 290KHZ.

Using a gate resistor of 22ohm.

how will the gate capacitance affect my high side of the driver at high frequency?

jzaghal

Joined: 31 Jul 2001
Posts: 219

26 Feb 2005 8:23 totem pole mosfet driver spice model

HI,

How does the highside look like in your circuit? are you using a specific driuver??

Also try using a 10 ohm resistor in the gate.

Bye.

poseidon_gal

Joined: 15 Dec 2004
Posts: 7

26 Feb 2005 16:52 and gate ckt

I am using IR2110

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JuergFrefel

Joined: 26 Feb 2005
Posts: 4
Location: Southern California

27 Feb 2005 20:58 Re: MOSFET gate drive circuit

I'm not able to see your picture due to some points limitation. I just signed up to this formum a few days ago.

A good way of finding out what is going on with a FET is to measure the Gate Source Voltage. On the highside this needs to be done by a differential measurement. I usually use a "cheater plug" to float the scope.
You also need a fairly fast scope since the rise and fall times are in the 100ns range.

The power disipation of the Driver can be calculated the following way:
On each transition the driver draws a current of roughly Vsupply/Rg for the duration of the switching time.
The energy per cycle is then: Esw = Vsupply * Vsupply/Rg * tsw
Assuming some numbers: Esw = 12V*12V/22Ohm * 100ns = 6.54e-7J

The power loss is then:
Ploss = Esw * fSw * 2 (since there are two transitions per cycle)
Ploss = 350mW

The whole part will see twice the loss rougly .7W, which is quite a bit for a small IC like that.

One thing I did in the past is glue a small piece of copper on top of the IC. This servers as a small heatsink.

poseidon_gal

Joined: 15 Dec 2004
Posts: 7

04 Mar 2005 17:28 Re: MOSFET gate drive circuit

hey...thanks everyone..for the help..

HINDI

Joined: 01 May 2004
Posts: 62
Helped: 1
Location: MISR "EGYPT"

05 Apr 2005 12:22 Re: MOSFET gate drive circuit

Hi

what i've understood that u want to build a gate driver using a dicreate componant .

see these links
http://www.irf.com/technical-info/designtp/dt94-12.pdf

http://matthieu.benoit.free.fr/moteur2.htm
salam
hindi