understanding Mosfet driver circuit

This is the circuit which i used to make for mosfet driving.
It used to work fine. But i then heared about Miller effect in mosfet. And then i heared about mosfet driver IC. "1R2110"
Which takes care of miller capacitance. (By providing a negetive current when turning off?? i am not clear).
I found this circuit in web for mosfet driver Totem pole configuration.
.

site says applying 5 volt to Vclk will turn on QH Bc817
but i see emitter is still open , Ib should be zero.
i need to understand totem pole configuration.

but i see emitter is still open , Ib should be zero.

Click to expand...

What do you mean exactly? Output voltage follows the input voltage minus Vbe threshold of 0.6V. Because the load is purely capacitive, all currents turn to zero after charging the gate.

please correct to my undertanding ,
As u said i will have in Vgs (eg 5 volt input then 5 - 0.7). But Ic is still zero(there is nothing to worry about Ic being zero).
But what is the use of the configuration. We could have directly given it.
After writing this reply i will search in google. Advantage of totem pole configuration

Purpose of the circuit is to provide high gate current during switching to charge/discharge the MOSFET gate fast.

A Mosfet Gate is a capacitor between gate and source.(This the capacitor you have shown in the diagram in the output -1nf and Vgs))
This capacitor must be charged to a voltage >=Vth when you want to switch the Mosfet ON.

To charge it quickly , the totem pole upper transistor helps.
Remember any delay in charging the cap , you will have delayed switch on.

So charge it fast with the upper transistor of totem pole.

To switch off the MOSFet , drain the charges from the gate quickly.
The lower transistor of the totem pole is turned-on and discharge the cap quickly.

The voltage in the input is almost available in the the o/p of totempole configuration.

For fast turn-on and turn-off of the FET , totempole configuration helps.

arya
for mosfet driver application use mosfet driver for better operation. if you do not have enough experience in power electronics.
in starting use IR2110 and application circuit is provided in datasheet also you can find my resource for ir2110.

its very important to choose appropriate gate resistor

@sribf Thanks sribf , you have explained it very well. And i am now clear with the circuit.
As abc_de and other resource in internet says use ir2110. Does IR2110 have similar circuit build in?
And taking cost into consideration and for normal application what is your take in choosing the configuration.
Does simple resistor circuit works best for 50 Volt and 2000Khz operation(i am afraid in this case)
or Totem pole configuration,
or IR2110. If u were in my place what will you choose?

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@abc_de "its very important to choose appropriate gate resistor" The gate resistor will be taken considering the graph between VDS and Id with different value of Vgs. ??
and i see IR2110 gives negetive potential for switching off, same question to you taking cost into consideration should i go for IR2110 or simple Totem pole configuration
when switching for voltage range of 50 volts 2000Khz frequency.

Your first circuit is very weak, 9.1Kohms is way out of
line for anything but a small signal FET. Also the collector
resistance in the opto will limit swing to half the supply
and you will likely saturate the opto BJT leading to large
turnoff delay. In both cases the FET Cdg (Miller) will
make drain transitions very slow. Solve
Vsupply/(9.1K/2)=Cdg*dVds/dt

I have designed IC MOSFET drivers with the Class B
style you show in the second figure. Worked OK, the
transient saturation of the final stage let them "kiss"
the rail without undue delay blowout, but the DC level
is Vce(predrive)+Vbe(drive) and this may give you
elevated FET leakage (rated at Vgs=0, what happens
at (say) Vgs=0.9V is all on you.

Your Cgg may or may not be 1nF but in any case it is
not (except in test figures) ground referred. Much or
most of it is FET drain to FET gate and this is where
your friend Miller takes a bite of your sandwich.

Hello Dick_free_bird i choose some value of 9.1K ohm and 9.1 Kohm resistor as i had a 12 volt source and i wanted to create 5 volt Vgs.
I choose any value in K ohm so i don't sink current. As with your comments i feel large value of resistor will reduce current sink of BJT and will create switching delays.
So should i go for 1k when i am making something very simple without totempole or Mosfet drivers?? or is it a complete bad circuit.

I didnt get "what happens at (say) Vgs=0.9V is all on you." Please explain. i guess .9 volt will come during my 5 to 0 transistion condition and at that voltage Mosfet will start turning off and there will be switching loss.
What can be done for that?

3rd paragraph i guess you are talking about situation when we are not doing negetive(ground) switching..(may be a circuit where there are more component in series to ground before switching).
yes in that case people use Mosfet drivers i guess.
Please comment more dick_free_bird.

Whether the resistor drive circuit is suitable, depends
on what you want at the load for transition time, etc.

Switching the load too slowly can impart a large slug
of thermal energy to the transistor die. There is a
pulsed energy limit and too much time spent dissipative
(not "off", not fully "on") can fry a device. This is the
reason (beyond switching efficiency) for wanting high
gate drive current capability.

Transistor specs such as "off" leakage are under one
well specified condition. For example you often see
"off" leakage at Vgs=0, Vds=max rated. But at Vgs=0.9V
(as you might see in an emitter-follower (Class B) style
as you showed) all you have to go on is "typical"
datasheet curves and any anecdotal bench data you
can generate for yourself (which excludes the range
of process variation, and so on).

As you have said in second paragraph yes i know well that Power = V X I ,and if current is more and v is near zero power loss in heat is near zero (when mosfet is on), and viceversa when mosfet if off.
The concern is during the switching time where both quatity p=V X I is max, if we reduce switching time we will be making an efficient system.